The US and its Arab allies are bombing IS. Why isn't Europe?

As the US expanded its fight against the so-called Islamic State into Syria alongside five Arab countries this week, the absence of European forces is noticeable.

European troops have been a staple of Western-led efforts in Libya, Iraq, and Afghanistan. Security officials consider the hundreds of European citizens who have gone to Syria to join the IS ranks to be the Continent's No. 1 internal security risk. And France, along with the UK and Germany – the three major military powers of Europe – have all agreed to arm the Kurds who are fighting against the Islamic State in their expansion into Iraq and Syria.

So where is Europe now, as the campaign against IS gets under way?

France

To date, France is the only European country to join the US and Arab states in any airstrikes at all. And it has done so only in Iraq, explicitly refusing to do so in Syria. French Foreign Minister Laurent Fabius reiterated Monday that his nation would not launch strikes in Syria at a Q&A at the Council on Foreign Relations.

When strikes against the regime of Syrian President Bashar al-Assad's over chemical weapons allegations were being considered last summer, only France stood ready to strike. Their hesitance to do so now is in part fear of doing anything that would bolster Mr. Assad’s hand – especially as they aid his moderate foes.

They also argue that they can act in Iraq because Iraq has explicitly asked them to do so – something that Assad has not, and almost certainly will not.

But France's defense ministry signaled Thursday that the government would consider an eventual strike on Syria. "The opportunity is not there today. We already have an important task in Iraq and we will see in the coming days how the situation evolves," Defense Minister Jean-Yves Le Drian said on radio Thursday morning. Asked about whether it was a possibility in the future, he said it was "on the table."

Britain

It appears that Britain, whose citizens IS has already killed and is threatening to kill more of, is getting ready to join the fray.

British Prime Minister David Cameron told NBC News on Tuesday that fighting the Islamic State is a fight "you cannot opt out of.” He said an international coalition was needed to “destroy” them. Parliament will be recalled on Friday to vote on the intervention.

But it has been slow coming, in part because as the US was signing up coalition partners and got France onboard, Britain was preoccupied by the Scottish referendum. If successful, that vote would have had an enormous impact on the structure of Britain, not least of which its armed forces.

Rosemary Hollis, an international relations expert at City University London, says that she expects that Parliament will also debate this narrowly, with no commitment to ground forces and only considering the Iraq question. Indeed, Labour leader Ed Miliband said he was "open to the possibility" of supporting air strikes against Islamic State in Iraq, he told the BBC.

That’s because Iraq specifically requested the support of British airstrikes, as they did with France. That leaves Mr. Cameron on solid political footing, after he failed to get Parliament’s green light to intervene in Syria last summer over Assad's chemical weapons.

Cameron told the BBC that any action against IS in Syria "would be a separate parliamentary debate. I want to be very clear about that."

Western Europe

The Dutch government is planning to contribute six fighter jets to the US coalition in Iraq against the Islamic State, reports Bloomberg. And Belgium is considering an offer of six more, the country’s defense ministry said, according to Reuters.

Germany has ruled out airstrikes – its decision in August to arm the Kurds was in itself a significant move for the conflict-weary nation.

Many countries across Europe have offered humanitarian aid, even if they are not getting involved in the fight.

But with time, as more hostages are taken or killed, and as Arab states take a more visible role in the coalition, Europe could be emboldened to add more to the fight, in Iraq and perhaps in Syria as well. “These people want to kill us,” Cameron said during his NBC interview. “They’ve got us in their sights, and we have to put together this coalition ... to make sure that we ultimately destroy this evil organization.”