TRAVEL-LOVING jihadists have long had a cause of choice, whether Afghanistan, Chechnya, Somalia or Yemen. At the moment it is Syria. Intelligence sources reckon that about 100 British Muslims are fighting in the country, mostly for the Islamist groups that make up the extreme end of the Syrian resistance. And worries are growing about what they might get up to when at last they come back to Britain. On April 25th Theresa May, the home secretary, announced that the government could withdraw the passports of those suspected of involvement in terrorist activities abroad who might return with “enhanced capabilities” to launch attacks at home. But, as with the Syrian civil war, the future is foggy.

Syria is comparatively easy to get to—just fly to Turkey and link up with a group that will get you over the border and into action. As a result, fighters can come and go regularly. By contrast, a trip to Somalia or Yemen has generally been one-way. That has helped Syria become one of the top destinations ever for foreign fighters, says Thomas Hegghammer, an expert on violent extremism at Stanford University. So alluring is Syria that jihadist groups in Chechnya and al-Qaeda in the Islamic Maghreb are urging people to stay put and fight the local fight, rather than doing battle on the streets of Aleppo.

Some will die on the battlefield (one dead Briton has already garnered a mention on a jihadist forum). Others will probably move on to fight elsewhere; some of those fighting in Syria cut their teeth battling against Muammar Qaddafi in Libya. Some may settle in Syria. Others will return to Britain and to their former, peaceful, lives—albeit perhaps with enhanced prestige among British Islamists. But a few may come back radicalised and ready to strike. Mr Hegghammer’s study of jihadists between 1990 and 2010 suggests that only about one in nine returning foreign fighters tries to launch attacks in the West. But their plots are more likely to succeed and twice as likely to kill people than those planned by terrorists who have never fought abroad.

British intelligence sources cite three particular worries. First, some of the British fighters may have already been inclined to attack their home country, but simply lacked expertise: they will acquire that. Second, they may be exposed to al-Qaeda’s ideology in Syria, and perhaps even talent-spotted as potential leaders. Third, the prospect of a large, ungoverned space close to Europe that could be used as a base from which to stage an attack on Britain is troubling.

Yet there is a big reason not to fear the returnees. Foreign conflicts are much more likely to produce domestic terrorists if they involve a group that wants to attack Western targets. Al-Qaeda in Afghanistan regularly trained foreign fighters and dispatched them westward. Syria boasts nothing similar. Jabhat al-Nusra, a jihadist group that has declared its affiliation to al-Qaeda in Iraq and which many British fighters are thought to have joined, has shown no interest in striking the West; its concern is toppling the regime of Bashar Assad. Whether the conflict in Syria leads to attacks in Britain will depend on whether groups like Jabhat al-Nusra decide to go global and encourage their British recruits to take the fight home. So far nothing indicates that they have. The warring in Syria is more than enough to keep them occupied. At least for now.