In aftermath of Paris attacks, how much security is enough?

An evacuated airport in London, spot inspections of vehicles in Belgium, semi-automatic rifles at top tourist sites: Europe has immediately stepped up security in the wake of the coordinated terrorist attacks in Paris that included suicide vests and the indiscriminate killing of 129 people.

As details emerge about who was behind the attacks at six locations in Paris Friday night, and how they were able to pull it off, governments are questioning holes in their own intelligence and whether more powers need to be granted to control potential suspects.

But the rampage in Paris, which stood out for its marauding nature and disparate targets, also raises an unsettling question. Can Europe command control of such an attack, amid geopolitical forces sweeping the Middle East. And if so, at what cost to the freedoms many on the Continent cherish?

Christian Mölling, senior resident fellow at The German Marshall Fund of the United States in Berlin, says Europe's response is being shaped at a delicate moment, where the potential for political polarization is clear, and is likely to color the debate on refugee policy and embolden the anti-immigrant far-right.

Praising French response thus far, Mr. Mölling says that increased security must not overshadow the larger goals. “This is not about protecting Europe as a territory, but protecting Europe as an idea and way of life.

“The immediate reaction of Parisians was to build groups, and say ‘I’m not afraid,’ ” he says. “It is a very good reminder of what Europe stands for. Because otherwise you declare defeat.”

Siege worries

Intelligence officials have been worried about a siege attack on European streets since the Mumbai attacks in 2008. There, a small band of fanatics was able to inflict mass damage in simultaneous action across a major metropolitan area.

The Metropolitan Police Service in London this summer carried out a mock operation based on such a scenario. But Sajjan Gohel, London-based international security director for the Asia-Pacific Foundation, says you can only prepare so much.

“It is very hard to deal with the threat once it’s unleashed," he says. "That is the very dangerous aspect of a marauding siege operation."

He says the most important security response is more coordination – between agencies in countries and between European nations.

France immediately called a state of emergency and put its military on maximum alert after Friday's attack.

Its neighbors in the region followed suit. The North Terminal at Gatwick airport outside London was evacuated after suspicion that a man of French nationality had disposed of what looked like a firearm. Metropolitan Police Commissioner Bernard Hogan-Howe told reporters that the “scale of the attacks and the range of weaponry used by the terrorists are a serious cause for concern.”

Italy raised its terror alert level, allowing it to rapidly deploy special forces if needed. Seven hundred soldiers were dispatched to heavily visited sites in Rome and beyond. Even Nordic countries sent officers with semi-automatic weapons to embassies or beefed up security at public gatherings like soccer matches.

Germany, in addition to strengthening border security, announced it was stepping up surveillance of its known extremists. "The situation is serious," Interior Minister Thomas de Maizière said Saturday. "We don't know whether the eight attackers we know of were all of them.”

It is unclear how coordinated the assault was across Europe and beyond. One of the attackers has been identified as French and known to security services. Another might have been a Syrian national who entered Europe along the migrant trail that is being used by, among others, those trying to escape the violence of the self-declared Islamic State.

An arrest along the German-Austrian border earlier this month, where authorities found explosives and firearms in a car, is now being investigated as linked to the Paris attack. Separately, Belgium announced three arrests on Saturday, including one suspect who is allegedly linked to a rental car in Paris tied to the attacks.

"Before and after the Charlie Hebdo attacks [in Paris in March], I have always said that not just single countries, but the whole West, including Germany, is in the crosshairs of international terrorism," Mr. de Maizière said.

Marc Hecker, a researcher on terrorism at the IFRI think tank in Paris, says he expects more announcements of tougher security, particularly ahead of big events like the climate conference in Paris that begins Nov. 30.

“From an EU standpoint, the threat is Europe-wide, especially in the UK, Germany, and Belgium. I think we can expect strengthened legislation especially for those countries who don’t have much right now,” he says.

Whatever it takes?

Residents of Paris, at least for now, say they welcome a bigger security apparatus. Outside the Petit Cambodge, one of the restaurants in the fire of the terrorists, Danielle Letourneur says she’ll accept “whatever it takes,” she says. “I am OK with more security, frisking, etc. We need to be safe.”

But François Huyghe, a cybersecurity specialist at the Paris-based think tank Iris, calls these measures symbolic, and more important as a form of “psychological support." In the wake of the Charlie Hebdo attacks in January, France had already greatly expanded its security, both with on-the-ground force and surveillance measures that some have likened to a French “Patriot Act.

“France had already toughed up its security and surveillance laws. It’s created a system to allow the government to see anyone who might be a potential suspect, but there are 5,000 of them, he notes. “There aren’t enough police officers to follow behind each one.”

In the Charlie Hebdo case, as well as in thwarted attacks since – including the Thalys train incident, when American servicemen overpowered a gunman – many suspects have already been on the government's radar. Short of tougher intervention in Syria and Iraq, Dr. Gohel says, Europe must focus on pre-emption through intelligence. “We are seeing a lot of examples where individuals were already known to authorities.”

But some French worry about going too far, especially in the emotional days immediately after an attack.

Antoine Lippen, a regular customer of the bars and cafes that came under fire in central Paris Friday, is one.

“Not whatever it takes,” he says. “It would be too dangerous to block our own liberties when we know terrorist attacks are always cowardly attacks attacking at the place and time you least expect it, so there is always a breach in security, whatever is imposed.”

Karim Emile Bitar, a Paris-based professor of international relations at Lebanon's Université Saint-Joseph, says that massive surveillance not only risks undermining democracy but could ultimately hurt counter-terrorism strategies.

“What is needed is human intelligence, intimate knowledge of Middle Eastern societies. Like the 19th-century anarchists, Islamist terrorists today want to ‘sharpen the contradictions’ within Western societies," he says. "Overreactions and a rise of extreme rhetoric would play in their favor. Governments should not fall into that trap.”