Can the UK protect itself from the danger presented by its citizens returning after fighting for ISIS — perhaps to continue the war at home? Prime Minister David Cameron believes that British security forces have the authority to take temporary steps to block their return, but wants Parliament to pass a law granting more permanent power to impose a de facto exile on British nationals who fight for ISIS and other terror groups:

British Prime Minister David Cameron announced Monday temporary enhanced powers for police designed to keep Islamist extremists in Britain from traveling to Syria and Iraq. Cameron told parliament that police would have the ability to seize the passports of suspected militants en route to Syria or Iraq. …

Cameron said authorities also needed stronger powers “to manage the risk by expected extremists already in the United Kingdom,” and those who may travel into the UK from other countries.

The plan would allow British authorities to confiscate passports from suspected jihadists before they leave the country as well as block re-entry for those who have already fought abroad. The demand for enhanced powers has civil libertarians raising red flags:

UK Prime Minister David Cameron has laid out his battle plan to counter the threat posed by Islamist extremists returning to Britain after fighting with terror groups overseas.

But already there are questions over how effective those measures would be, whether they are legal and whether Cameron, who heads a coalition government, can push them through Parliament.

“Dealing with this terrorist threat is not just about new powers, it is also about how we combat extremism in all its forms,” said Cameron as he announced his plans on Monday.

Part of the skepticism comes from the lack of specifics so far from Cameron, as well as the de facto exile it will produce:

Cameron said that among the measures envisaged was a plan to give border police powers to seize passports from departing would-be jihadists and restricting the movement of suspects.

But he failed to give details or a timetable for implementation and said a proposal to block suspected fighters from returning to Britain was being looked at.

The proposal is a controversial one in international law as it would be illegal to make British nationals “stateless”.

“He is doing all he can to sound tough without having the detail in place to back up the rhetoric,” wrote Rachel Sylvester, a political commentator for the Times.

She cited the former head of public prosecutions Ken Macdonald as saying that officials were in “la-la land” if they thought the idea of blocking jihadists would be accepted by the international community.

Where would the British jihadists go, if not back to the UK? Would they be arrested, or simply end up stuck in an airport indefinitely, unable to move in any direction? The Financial Times noted that this could end up putting Turkey on the spot to house the jihadists, as many of them traveled through Turkey to get to the front lines. That might make Turkey less cooperative in dealing with the situation it helped create in Syria in its haste to get rid of Bashar al-Assad. The notion of stateless exile may well have other nations concerned, too, who will eventually have to deal with the problem.

Still, at least the UK appears to be looking for specific solutions to deal with the problem of returning jihadis. The US and other nations who have nationals fighting in ISIS appear to be dealing with the threat with much less alacrity. Lacking specifics may be a problem for Cameron, but lacking any direction is a much bigger problem for the others.