Evan Vucci/AP

President Trump and NATO leaders watch a flyover during a ceremony at the North Atlantic alliance's new headquarters, Thursday, May 25, 2017, in Brussels.

The “family photo” of leaders attending the NATO meeting in the Belgian capital Thursday included an unusually large number of first-timers to the transatlantic alliance’s premier stage.

Among the newcomers pictured in the traditional summit souvenir was the president of tiny Montenegro, whose country only acceded to NATO membership in April.

Yet even that distinction paled in comparison to the attention accorded two other first-timers to a NATO leaders’ gathering: US President Donald Trump and French President Emmanuel Macron.

All eyes remained focused for the duration of what amounted to a brief mini-summit of the two leaders – both elective-office debutants as well – who seemed to arrive on the NATO stage from out of the blue.

More intriguing and irresistible still was how the two presidents – one a brash showman with populist tendencies and prone to dark statements about America's challenges, the other a prim technocrat with a global outlook and sunny disposition – encapsulated the opposing forces pushing and pulling on alliance countries and on the West more broadly.

“What’s going to stand out about this [NATO meeting] is the family photo, it will be worth keeping a copy of this one,” says James Townsend, a former deputy assistant secretary of defense for European and NATO policy. “There will be President Trump and President Macron together on the same stage,” adds Mr. Townsend, now a senior fellow in transatlantic security at the Center for a New American Security in Washington. “Who would have thought that photo was even possible just a few months ago?”

Beyond the lingering incredulity over the two leaders’ unlikely rise is a fascination with how they were lifted to political power by seemingly opposite waves of public fervor.

Opposites

For as much as Mr. Trump has come to symbolize internationally a populism that would build walls, turn inward, and protect national identities and economies from global influences like trade and migration, Mr. Macron in a few short weeks has risen to represent the answer to the Trump backlash.

Where Trump is America First, Macron is a multilateralist. Trump is pro-Brexit, Macron is pro-European Union. Where Trump is a nationalist, Macron is an internationalist who would rather make globalization work better than resist it.

Moreover, Trump is perceived by many in Europe as harking back to a bygone era, whereas Macron is seen as innovative and focused on the future. And indeed, it’s Macron’s youthful can-do spirit – traditionally more often considered an American trait – that has given the French leader almost Obama-esque rock-star appeal and popularity beyond France’s borders.

When presented with the distinct visions offered by the two leaders, Europeans largely favor Macron's, if polls are to be believed.

Evan Vucci/AP

President Trump shakes hands with French President Emmanuel Macron at the US Embassy in Brussels on May 25, 2017

“I dare say in Europe the optimist Macron’s view of the world carries the day, because it gives people something to believe in,” says Sven Biscop, director of the Europe in the World program at the Egmont Royal Institute for International Relations in Brussels. “Trump’s view offers just despair and scapegoats.”

Or as the Belgian daily Le Soir put it in a front-page commentary, the simultaneous international debuts of Trump and Macron revealed to other leaders and to the public “the negative star and the positive star” of the NATO meeting.

It’s hardly surprising that Belgians in particular among Europeans would dislike Trump, given his derision during the presidential campaign of the EU and his indelicate description of Brussels – home to NATO, the EU’s administrative headquarters, and the Belgian government – as a “hell hole.”

But some here say that Europeans should remember that the same contrasting qualities they are seeing in Trump and Macron are present in their own countries. Macron’s victory did not spell the end of nationalist populism in Europe, they say, any more than Trump’s unpopularity in Europe means he does not appeal to a white working class that feels left behind by the world Macron touts.

“The tension we see in America between the nationalists and the more internationally oriented, between protectionism and globalization, or between those who support immigration and those who don’t, we have the same happening in Europe,” says Bruno Lété, transatlantic fellow for security and defense policy at the German Marshall Fund of the United States in Brussels.

Indeed, those same divisions have been on display in the Trump administration, Mr. Lété says. But he adds that Europeans who favor strong transatlantic relations are heartened by indications that the administration’s internationalists are winning the debate in the White House.

“It looks to us like despite whatever he may have said, Trump is going with the people in his administration who are more supportive of multilateralism, more pro-alliance. That’s the people like [Defense Secretary James] Mattis and [Secretary of State Rex] Tillerson,” he says.

Liking Macron, needing Trump

And as for contrasting the leadership styles of Trump and Macron, Lété says that is not a preoccupation of transatlanticists since no French president – no European leader for that matter – replaces the key role of the American president and American leadership. “Macron is not going to define himself and his policies within NATO,” he says. Trump, on the other hand, “is critical to the transatlantic relationship” because without America “there is no partnership.”

What defines Macron is a mix of pragmatism and optimism that makes him attractive, Lété says. Those same qualities appear to be offering a new model of leadership to Europeans who see little to like in Trump but who at the same time understand the importance of forging a relationship with the American president.

Belgian Prime Minister Charles Michel is one of those Europeans. The young leader with a shaved head and a trimmed beard wants to be like Macron, but he wants to be able to work with Trump.

“Macron is one of a number of European leaders I want to join who want to give people a new project, a new reason for hope,” Mr. Michel told journalists he met with for an informal conversation Wednesday night. “We favor reform and want to encourage innovation.”

Those words reflect the sense of relief and of renewed purpose that have pervaded much of Europe since Macron’s victory – replacing the sense of doom that had settled in like a fog after July’s Brexit victory.

As for Trump, Michel turned aside journalists’ questions about the president’s record of anti-European and anti-Belgian pronouncements, instead focusing on areas of common accord.

“I heard a different perspective from President Trump,” the Belgian leader said just hours after meeting with him. “He wanted to talk about burden-sharing, and I agreed that Europe must do more” to pay for its own defense.

Trump’s firm belief that America gets a raw deal from Europe on both security and trade is likely to carry over to the G7 summit he’ll attend beginning Friday in Sicily. But in Brussels, according to the Belgian leader’s summation of their meeting, the focus was on cooperation.

Michel said he cited the threats facing Europe, from Russia to the east and instability to the south, and from terrorism. He reported saying that addressing those challenges must proceed through the two sides of the Atlantic working together – and he said he got a rhetorical thumb’s up in response.

“I asked him, and he said he agreed,” Michel said, “that there must be unity between the United States and Europe.”

Evan Vucci/AP

A man screams at reporters during a campaign rally for Republican presidential candidate Donald Trump at Lackawanna College, Monday, Nov. 7, 2016, in Scranton, Pa.

Lots of politicians aren’t happy to see reporters. From the point of view of elected officials, the press comes at them from all angles, always wanting answers. It’s tough to free yourself. It’s like they’re a swarm of ants.

Lots of politicians have demeaned reporters for partisan purposes over the years. It’s been almost five decades since Vice President Spiro Agnew roused GOP voters by calling the media “nattering nabobs of negativism” (words penned, perhaps ironically, by future New York Times columnist William Safire).

But as US politics becomes increasingly polarized and partisan a heightened tone of hostility may be seeping into the relationship between reporters and the politicians they cover.

On Wednesday Greg Gianforte, a Republican candidate for Congress in Montana, physically assaulted a reporter asking a question about health care.

Last week, Federal Communications Commission security pinned a reporter against a wall after he tried to question FCC commissioners. And earlier this month, West Virginia police arrested a veteran reporter for trying to question Secretary of Health and Human Services Tom Price in the state capitol.

President Trump’s depiction of the mainstream media as lying, grasping, and a failure – and a large number of Americans who agree – may have shaped the environment in which these events occurred.

The bottom line: This rolling ball of conflict doesn’t help either side. The press, in particular, is vulnerable to further erosion of its position. Technology long ago cracked open the old mainstream media’s ability to define what is and isn’t news. Now Mr. Trump’s tweets and the insidious rise of fake news are going after what’s left of mainstream media credibility.

“I don’t look for the situation to improve anytime soon,” says Jeff McCall, professor of media studies at DePauw University in Greencastle, Ind., via email. “The press needs to step up its professional behavior and societal leaders must be more open to public scrutiny. There’s little evidence now that either of those things are ready to happen.”

Freddy Monares/Bozeman Daily Chronicle/AP

Greg Gianforte, the Republican candidate for Montana’s only US House seat, was accused by a reporter of having “body slammed” him Wednesday, the day before a special election.

It’s the Gianforte incident in Montana that suddenly inserted this subject into Americans' social media news feeds. Gianforte, the GOP candidate for an open House seat in Montana and former wrestler, grabbed a reporter for the British newspaper The Guardian around the throat and body-slammed him to the ground. His anger was apparently sparked by a question about the new Congressional Budget Office analysis of the cost and coverage of the Republican health-care bill. According to an audiotape and three eyewitnesses from Fox News, the candidate reacted violently only a few seconds into the conversation.

Mr. Gianforte’s office initially blamed the reporter, Ben Jacobs, citing “aggressive behavior from this liberal journalist.” The campaign's version of events is not borne out by the tape of the encounter.

Gianforte has not apologized for the alleged attack, which has upended an election that ends with voting today. Local authorities charged him with misdemeanor assault.

Tension between candidates and reporters is natural, note media experts. Campaigns are tiring and emotional. Journalists push tough issues, such as the GOP effort to repeal Obamacare, which candidates and their staffs may view as things they would particularly like to avoid.

That said, it’s not natural for a candidate to snap and turn an encounter into a wrestling match. It may have been only a flawed personal decision. But it also may have been a flawed personal decision made in a larger cultural context, says Paul Levinson, professor of communications and media at Fordham University in New York.

“There’s no doubt that the contempt and hostility expressed by Donald Trump toward the press, both in the campaign and continuing in his presidency, has created a climate in which unstable politicians who can’t control their violent impulses, like Greg Gianforte in Montana, act out their violence and physically attack reporters,” says Professor Levinson.

A question, then an arrest

The physical restraint of an inquiring reporter at the FCC and the arrest of a journalist questioning HHS Secretary Price in West Virginia weren’t as violent, but in some ways were just as troubling, say other media analysts. The reporter in the FCC incident, John Donnelly of CQ Roll Call, is a respected Washington veteran. He was shadowed by guards as he walked the FCC halls, as he is allowed to do. When he approached a commissioner for an inquiry, guards backed into him and pinned him against the wall.

The reporter in West Virginia, Dan Heyman, who works for Public News Service, was standing in a hallway when Price approached. (Price was in town to study the opioid crisis.) Mr. Heyman said he “yelled out” a question on the treatment of pre-existing conditions in the GOP health bill. Price didn’t answer, so he tried again. The Secret Service then handcuffed and arrested him and charged him with “willful disruption of government processes.”

The facts of these cases matter. Further description could put them in a different light. Still, they may be symptoms of today’s media age, says Aram Sinnreich, professor of communications at American University in Washington.

“There’s a common thread uniting many of these incidents,” says Professor Sinnreich. “Trump’s consistently incendiary language against the press, the administration’s overt antipathy and exclusion of the press, and the tacit or explicit celebration of this rhetoric.”

When truth gets politicized

The point of these attacks, according to Sinnreich, may be to undermine the credibility of journalism as an enterprise. It’s similar to the way some conservative attacks on climate change theory charge that scientists are politically motivated. It’s an effort to erode the authority of experts.

“To many people, the journalistic method, like the scientific method, just becomes another arbitrary and politicized type of truth claim, with no logical or moral high ground,” says Sinnreich.

Other experts don’t see these incidents as being so indicative. Especially in the Gianforte case, a punch might be just a punch. There have been previous descriptions of Gianforte as being inexperienced and thin-skinned for someone running for such a visible political position.

“Maybe this is more about him in this case rather than anything else,” says Patrick Miller, a professor of political science at the University of Kansas in Lawrence, who studies partisanship and polling methods.

Angry politicians have been known to physically assault each other, Professor Miller points out. One person can explode. The point now is for the GOP as a whole to condemn the action, he says. Otherwise the larger organization appears to condone it.

“Parties have to enforce norms,” Miller says.

Press credibility declining before Trump

And while it’s true that Trump has skillfully exploited the public’s fears and concerns about the press during his campaign, it’s not as if he was attacking institutions held in august regard by the public. The standing of the press has been declining for years, notes Professor McCall of DePauw University.

“The press’s credibility has declined by fifteen percentage points in fifteen years, so public perception of media decline was well underway before the Trump campaign,” McCall says

The public just no longer believes the media has citizens’ interests in mind, according to McCall. It sees news outlets as too sensational and eager to profit and driven by their own particular agendas.

“Overall, there is little sense today in America about what a free press was created to do,” McCall says.

Fifteen years ago, when China and the 10-country Association of Southeast Asian Nations committed to establishing a code of conduct to govern actions in the South China Sea, the Paracel Islands were little more than a collection of rocks 138 miles off the coast of Vietnam.

They’re now home to Chinese harbors, helipads, and an air base. Last year, Beijing deployed anti-aircraft missiles to the archipelago. And satellite images released earlier this year by Center for Strategic and International Studies in Washington show that more work is being done in likely preparation for further construction. 

China’s militarization of the South China Sea, a vast waterway through which more than $5 trillion in trade passes each year, faced sharp criticism from the Obama administration, which regularly ordered freedom-of-navigation patrols to challenge Beijing’s territorial claims in the area.

Having criticized former President Obama for not doing enough to counter China, Donald Trump took over the White House seeming eager to up the pressure. For the first four months his presidency, however, it looked as if the US had decided to back off, perhaps seeking Beijing’s cooperation on North Korea or other concessions on issues such as trade. That appeared to change on Wednesday, when a US Navy destroyer sailed within 12 miles of one of China's man-made islands in Mischief Reef, in the Spratly Islands. 

The patrol, the first of its kind since October, marks the Trump administration’s first public foray into the South China Sea dispute. But analysts say it’s far from enough to alleviate concerns among US allies that the White House is unwilling to confront China on the issue – or diminish Beijing’s efforts to expand its influence in the region. 

“The operation sends a long overdue signal in the South China Sea that the United States does not recognize China's spurious claims to water and air space around its artificial islands,” says Mira Rapp-Hooper, a senior fellow in the Asia-Pacific Security Program at the Center for a New American Security in Washington. “But this administration is going to have to do more than just conduct a single passage with one naval vessel to convince Southeast Asian nations that it's invested in freedom of navigation over the long haul.”

New code of conduct

For now, Dr. Rapp-Hooper says, China will keep arming its artificial islands while pushing ahead on the diplomatic front. The country’s latest diplomatic breakthrough came last Thursday, when it reached an agreement with the Association of Southeast Asian Nations (ASEAN) on a draft code of conduct in the disputed waterway. Details of the draft weren't disclosed, but the framework agreement came as a sign of progress after 15 years of stalled negotiations. It will next be presented to Chinese and ASEAN foreign ministers in August for consideration.

Rapp-Hooper says the code of conduct is far from a done deal and that there is likely much left to negotiate. Still, she says the timing of last week’s announcement signals China’s push to reinforce its position in the South China Sea at a time when US policy for the region remains unclear.

“China is basically now in a position to consolidate its gain,” Rapp-Hooper says. “It’s built what it wanted to build. Now it can use the code of conduct to say to the other South China Sea claimants, ‘We know it’s been a rough few years, but we’re willing to play ball now.’ ”

Analysts say Beijing’s ultimate goal is to pull Southeast Asian nations closer into its orbit, disrupting the post-World War II order that paved the way for the US to become a dominant power in Asia. In the short term, Beijing wants to prevent Washington from influencing its negotiations with other countries that border the South China Sea. China claims virtually the entire sea, while the Philippines, Malaysia, Brunei, Vietnam, and Taiwan claim parts.

Last July, an international tribunal at The Hague's Permanent Court of Arbitration concluded that China's claims to wide-reaching sovereignty over the sea had no legal basis, although Beijing boycotted the proceedings and rejected the decision. The case was brought by the Philippines under former President Benigno Aquino III, but his successor, President Rodrigo Duterte, has downplayed the tribunal's decision as he pursues stronger ties with China. 

“History and facts have proven that countries in the region are fully capable of handling the South China Sea issue themselves,” Xinhua, China’s state news agency, said in a commentary on Monday. “Any outside noise should be drowned out.”

Jacob Turcotte/Staff

Balancing act

Much to the delight of Beijing, the Trump administration hadn’t made much noise until Wednesday. Previously, the administration’s strongest criticism came during Secretary of State Rex Tillerson’s confirmation hearing, when he suggested that China should be denied access to the islands it built. Despite his harsh words, the Pentagon later turned down three requests from the US Pacific Command to conduct freedom-of-navigation patrols (FONOPS), The New York Times reports.

A statement from Pentagon spokesman Maj. Jamie Davis gave no details of recent patrols, but said that “US forces operate in the Asia-Pacific region on a daily basis, including in the South China Sea. All operations are conducted in accordance with international law and demonstrate that the United States will fly, sail, and operate wherever international law allows.”

“FONOPS are not about any one country, nor are they about making political statements.”

Carlyle Thayer, an emeritus professor at the University of New South Wales in Australia, says the prolonged suspension of freedom-of-navigation operations fueled concerns that the US would stop trying to counter China’s growing influence in the region. Without support from the US, smaller countries could begin to see China as the region’s most dependable power. Regional dynamics are already shifting, such as Mr. Duterte's pivot toward China while distancing the Philippines from the US, a longtime ally.

“China’s line is that the US should not interfere [or] disrupt China-ASEAN diplomacy,” Dr. Thayer says in an email. And with the Trump administration’s protracted show of deference toward Beijing, he adds, it was “going along quite well.”

After this week's patrol, however, Chinese officials said they had lodged a complaint. 

“We urge the US to correct this mistake and stop taking further actions so as to avoid hurting peace and security in the region and long-term cooperation between the two countries,” said Lu Kang, a spokesman for the Foreign Ministry.

China is a long way from displacing the US from the South China Sea or Southeast Asia, says Tiffany Ma, senior director of political and security affairs at the National Bureau of Asian Research in Washington. For one thing, the US still maintains a large military presence in the region. In January, the Philippine defense ministry announced the US would upgrade facilities at military bases across the country this year, although Duterte had previously called for some US troops to leave. 

“This is a balancing act countries in Southeast Asia have been walking for a long time,” Ms. Ma says. “The broader question is whether the US is committed to maintaining the post-World War II order that has come to define the region.”

Editor's note: This story has been updated to clarify which legal body heard the case over China's claims in the South China Sea. It was an international tribunal at the Permanent Court of Arbitration, in The Hague.

Ernest Scheyder/Reuters

Workers from ScanDrill Ltd clamp together pieces of pipe while drilling an oil well for Jagged Peak Energy Inc near Fort Stockton, Texas. The state has helped lead a boom in US oil production, which has dampened OPEC's ability to lift global oil prices.

For years, the world oil market has acted like a seesaw, balancing the world’s motorists against oil producers. After the Great Recession, producers were on top, raking in profits from high oil prices.

Then, three years ago, the positions shifted. Oil prices plunged and motorists were riding high. Cheap gasoline put billions of dollars in their pockets, while producers struggled to pay bills.

Now, the teeter is beginning to totter again – and motorists, as well as trucking companies, airlines, and other oil consumers, could land with a thud as oil prices rise.

No one knows when this will happen. Prices could push to $100 a barrel or more by the end of next year, according to the most aggressive forecasts. Or they could stay at current levels for the next five years before rising.

What is clear is that the forces holding prices down are beginning to dissipate. A meeting of OPEC nations is bringing some of the changes into focus, and it’s a reminder that the industry that literally fuels the global economy defies simple narratives. Oil-producing nations may no longer have quite the clout that they once did, but neither is an “end of oil” shift to clean energy already ascendant.

And all this has repercussions for both consumers and the wealth of oil-reliant governments from Russia to Africa.

“Markets don't work quietly,” says Dan Dicker, an oil trader and analyst who writes the Energy Word blog letter. “When trends start developing, they go overboard – on both sides.”

The latest move came Thursday when the Organization of Petroleum Exporting Countries announced that it is extending for nine months an existing agreement to cut production. The original agreement called for OPEC members to cut 1.2 million barrels per day (b.p.d.) of production and for 11 nonmembers to trim an additional 600,000 b.p.d. Prices shot up 9 percent in a day.

If OPEC can maintain the discipline it has shown in the previous six months, it could begin to draw down the glut that has built up over the past three years because of overproduction, according to the International Energy Agency.

Already, the IEA reports that oil supply and demand are in rough balance and demand is climbing.

US fracking's surprising rebound

Looking beyond the next five years, oil prices appear bound to go up because the oil majors slashed their exploration budgets when prices were low. Thus, when maturing fields fall out of production in a few years, there will be very few oil discoveries to replace them right away.

The spoiler, which could keep prices weighed down for a while, is the US shale industry. Left for dead 18 months ago, when oil prices dipped below $40 a barrel, US producers have staged an unexpected comeback, slashing costs and ramping up production. US crude output has jumped 10 percent in a year, and now nearly rivals the leaders, Russia and Saudi Arabia.

Shale companies could boost their output by nearly 800,000 b.p.d. this year, according to the IEA. That would counterbalance nearly half the cuts that the OPEC deal is supposed to maintain.

US output could grow even more if oil prices don’t crash again.

“We expect the US can grow oil production for 10 years or a little longer,” R.T. Dukes, research director for energy consulting firm Wood Mackenzie, writes in an email. That assumes that oil prices gradually move up to around $70 or $80 per barrel. But even in the current range of $45 to $55, “we think the major plays will grow.”

That makes the US shale industry ​– and the jobs that go with it ​– a big winner in the current environment.

A wild card: electric cars

But a rise in oil prices could make winners, also, of both green energy alternatives and oil-reliant nations in places like Russia and Africa.

The higher prices go, for one thing, the more consumers and carmakers have an incentive to invest in electric cars.

“For the first time in a century, there is a real chance that the automotive ecosystem could change considerably in the years ahead,” says Jim Burkhard, head of oil market analysis at market researcher IHS Markit in Washington. It could end “oil’s de facto monopoly as a transport fuel.”

A twist, of course, is that the faster a transition toward electrified transport occurs, the more it will dampen demand for oil. But it will take a minimum of 15 years for electrification to eliminate growing oil demand, says Antoine Halff, senior researcher at Columbia University’s Center on Global Energy Policy in New York. But even if it doesn’t happen for years, “a peak in demand for 2040 has implications for how the Saudis should maximize their resources starting now.”

Russia vs. Venezuela

In the near term, geopolitics is also in play. Oil-exporting nations that have been struggling economically would benefit from a price rebound. One of them is Russia, which has agreed to cooperate with OPEC by trimming back production. Among the most financially stressed of the oil-producing nations, Russia is finally showing signs of coming out of its deep recession.

By contrast, Venezuela, the other nation most stressed by low oil prices, looks to be a loser. A price recovery will probably not come in time for the regime, which has so mismanaged the economy that citizens are rioting in the streets.

Big consequences could also be expected across much of Africa, with its many oil-producing nations from North Africa to further south.

Several sub-Saharan African countries ​– prominent among them Nigeria, the continent’s largest economy, and Angola ​– have staked their post-colonial fortunes on oil, and grown to become some of the world’s largest producers. But the oil producers, which include countries like the Republic of Congo and Sudan have often fallen prey to the toxic mix of corruption, low development, and economic volatility commonly dubbed the “resource curse” ​– a shorthand for the paradoxically adverse effects that resource extraction tends to have on developing economies in Africa and elsewhere.

Africa's mixed response

Africa’s oil producers are undoubtedly behind the global curve in diversifying their economies, says Mercy Ojoyi, a researcher in the African resources program at the South African Institute of International Affairs, and an expert on sustainable development in Africa.

“We certainly aren’t seeing any African Dubais yet. They just don’t have the diversified economies at this point, though many are trying to move in that direction,” she says. Still, for the time being “they continue to suffer heavily economically and socially when prices change.”

Smaller countries like the dictatorial Equatorial Guinea, which has had the same president for 38 years (the longest-serving president in the world), where oil accounts for 90 percent of government revenue, are among the worst-off at present.

“There’s essentially no economic activity there besides the oil and gas sector,” says Ben Payton, head of the Africa division for Verisk Maplecroft, a Britain-based consultancy. He says oil revenues tend to line the pockets of a small elite while the rest of the country remains shockingly poor. A rebound in oil prices by itself won’t change that.

But in Nigeria, the rise of alternative industries like telecom, construction, and agriculture – buoyed by the circulation of oil money in the country – at least partially insulates the country from price shocks and other fluctuations in the oil market.

Exempt from the last round of OPEC production cuts on account of infrastructure damage by militants last year, Nigeria has seen attacks go down and output rise. By June, Nigeria says it should be back to full production at 2.2 million b.p.d., up 1 million b.p.d. from April’s figures.

The Saudi factor

Globally, Saudi Arabia remains a key player to watch. It almost single-handedly created today’s glut of oil by ramping up production three years ago in a bid to maintain its market share and drive out US shale producers. When that didn’t work, it changed course six months ago and engineered the OPEC deal that has lifted prices and will begin to whittle down the glut.

The potential boom in electric transportation, like the resilience of US shale producers, complicates the Saudi calculus.

But no one knows how that will play out, Mr. Halff says. “History shows that the market can always surprise you.”

Ryan Lenora Brown contributed reporting from Johannesburg.

Courtesy of Uwe Schmidt/Smithsonian Tropical Research Institute

A common vampire bat mother with young.

It pays to share widely, because you never know when you might need a friend to go to bat for you.

At least that’s the strategy employed by the common vampire bat, according to new research. A study published Tuesday in the journal Biology Letters found that female members of the species who had previously shared their meals with a greater number of non-relatives tended to fare better during hard times than those who invested in smaller social networks.

These findings add to a growing body of evidence that humans are far from alone in forming friendships, that is, preferential associations with non-relatives, social bonds that appear to run deeper than straightforward tit-for-tat exchanges. The bat’s strategy, which the researchers call “social bet hedging,” may play a role in shaping cooperative behavior in other species, including our own.

“Understanding how individuals make cooperative investments based on the returns in more ‘simple’ social bonds, like in food-sharing vampire bats can help us understand the foundations of more complex relationships like those among humans,” says lead author Gerald Carter, a postdoctoral researcher at the Smithsonian Tropical Research Institute in Panama.

Dr. Carter describes Desmodus rotundus, the scientific name for blood-slurping bat native to Central America and South America, as “a great organism to study for insights into cooperative relationships.” Wild females and their young will often roost in groups of eight to 12 in caves or hollow trees, which they leave each night in search of a meal, one that typically dribbles from the bites they inflict on chickens, pigs, dogs, and other animals (human blood is rarely on the menu). Because their blood-only diet contains so little fat, the bats cannot store energy for very long: Those who go two or three nights without feeding starve to death.

When a female bat fails to secure a meal for herself, as happens with about a third of juvenile bats and about 7 percent of adults each night, she will groom her roost-mates in the hopes that they will regurgitate some of their partially digested meal into her mouth. Help often comes from mothers, daughters, or other kin, but bats will also often share their food with unrelated individuals – their friends.

In research conducted in Costa Rica in the 1970s and 1980s, biologist Jerry Wilkinson observed bats refusing to feed roost-mates that had previously snubbed them, and he quantified the costs and benefits of such sharing. These insights, combined with the relative ease with which researchers can replicate the conditions that promote this behavior, have made the bats a model species for studying what biologists call reciprocal altruism, a behavior in which one organism makes a sacrifice to help another, with the expectation that the favor will be repaid.

“The most frequent assertion is that vampire bats are exhibiting tit-for-tat,” says Dr. Wilkinson, a professor at the University of Maryland and a co-author on this newest paper. “The more recent work that Gerry Carter did for his PhD under my supervision indicates that the bats are not engaging in strict tit-for-tat, but they are reciprocating over a longer time interval.”

In 2015, Carter and Wilkinson found that the bats would sometimes appear to forgive roost-mates who declined to help because they didn’t have enough food to share, and bats who had previously been unable to help would be especially generous later on, almost as though they were compensating for past stinginess.

In other words, each bat appears to navigate a complex social environment, one where she must to keep track of who snubbed her – and for what reason – while also working to repair relationships that have been strained.

This most recent finding, based on a four-year study of about 30 captive bats, builds on this research. Some bats feed more non-relatives than others, and those who cultivated weaker ties with a larger number of friends would usually be fed as often as those who forged stronger bonds with a few friends.

But when the researchers separated a bat from her primary donor, typically her mother or daughter, the benefits of having a bigger social network became apparent. Bats who had invested in quantity instead of quality had an easier time finding donors. Their friends helped them cope with the loss.

“When I very first plotted the data, I was overwhelmed with surprise and joy that it looked exactly how I thought it should,” says Carter. “That is a very rare thing in science.”

“I was surprised to see such clear evidence for the value of having backup partners. We’ve not seen that before,” says Joan Silk, an anthropologist at Arizona State University who has studied social relationships among baboons.

“The great contribution of this paper is that it provides evidence about a completely new way in which having relationships matter,” Dr. Silk says. “It makes sense that if relationships are important for individuals, then strategies to deal with the loss of partners may also be very important.”

Like female vampire bats and humans, female baboons are known to form close ties with non-relatives, and they tend to spend more time grooming more partners following the death of a female relative. Humans tend to report greater happiness from having a small number of close friends as opposed to a larger network of weaker ties, but in environments where friends are likely to leave, quantity matters more than quality.

Among humans, baboons, and bats, these strategies likely operate outside of conscious awareness: pursuing and maintaining friendships does not require any deliberate calculation of the costs and benefits. “In many situations, our first impulse is often cooperative,” says Carter. “We feel emotionally compelled to help others,” he says, “because natural selection has done the calculations for us.”

“You don’t ask your friends to exchange 25 minutes of emotional support for two dinners at your house,” he says. “That’s not how friendships work at all.”

Reuters

NATO country leaders greet at the start of the NATO summit at their new headquarters in Brussels, Belgium, May 25.

During his first official trip to Europe this week, President Trump was politely asked to back the defining glue of the Continent and the transatlantic partnership. Both the European Union and NATO – the core of what is called “the West” – have enough issues without the uncertainties of Mr. Trump’s “America First” theme of the past year. The West, advised European Council President Donald Tusk, needs to focus on “values ... not just interests.”

Both the EU and NATO are too often defined by what they are against, such as Russian aggression, trade protectionism, terrorism, and anti-democratic forces. This approach alone can lead to splits over the nature of the threats or how to respond to them. Britain, for example, is leaving the EU because of differences over risks such as refugees. Yet safety and prosperity for any alliance of nations are best assured through a higher and collective practice of shared ideals.

“Values and principles first, this is what we – Europe and America – should be saying,” Mr. Tusk said. He listed a few of the values as freedom, human rights, and respect for human dignity.

A values-first approach helps Europe and the United States make the necessary sacrifices for a greater good. After some initial waffling, for example, the Trump administration has lately reaffirmed a US commitment to NATO’s mutual defense pledge, known as Article 5. That will be comforting to Poland and the Baltic States, which border Russia. And since 2014, after the Russian taking of Ukrainian territory, most NATO members have responded to a US concern and are steadily raising military spending to 2 percent of their gross domestic product by 2024. NATO has also promised to assist the US more in the struggle against Islamic State and may do more in Afghanistan.

The EU also seems to be avoiding any further drift toward hard-right nationalism. The May election of centrist Emmanuel Macron as French president, as well as the expected reelection of Chancellor Angela Merkel in Germany this fall, show that the core nations of Europe remain committed to the Union’s promise of continental peace and economic openness.

Just as hopeful is the continuing desire of a few more former Soviet-bloc states to join the EU or NATO. The tiny Balkan nation of Montenegro, for example, is set to join NATO next month while Ukraine and others are on track to join the EU.

The idealism of both the EU and NATO – and not just the nationalist “interests” they might fulfill in membership – remains a big draw. Both are no longer merely regional or transatlantic bodies. By standing for universal values, they have become a global force for good. No matter what new threats or issues come along, their “glue” holds them together.