British Prime Minister David Cameron called Monday for a new law to give police the temporary power to seize a passport in case a British citizen is suspected of trying to travel to support ISIS.
"Passports are not an automatic right," Cameron told lawmakers meeting in the House of Commons on Monday. He said "specific and targeted" legislation should be introduced giving police the power to seize passports with "appropriate safeguards."
The legislation to allow this would begin to be prepared immediately, Cameron said.
The Prime Minister also announced he would introduce legislation giving British authorities new powers that would strengthen their ability to track suspected supporters of ISIS, by providing "enhanced use of exclusion zones" or "relocation powers."
The UK government raised its terror threat level Friday from "substantial" to "severe" -- the fourth of five levels in response to events in Iraq and Syria, where ISIS militants have seized a large swath of territory.
"That means that a terrorist attack is highly likely, but there is no intelligence to suggest that an attack is imminent," Home Secretary Theresa May said.
The "root cause" of Britain's terror threat is "Islamist extremism," Cameron said Friday. The execution of American journalist James Foley is clear evidence that ISIS' fight in Iraq and Syria "is not some foreign conflict thousands of miles from home that we can hope to ignore," the UK leader said.
ISIS is unlike other Islamist extremist groups in its primary focus not to find a country that can be its base of operations, but to create its own country. And the group has had ample success in that regard, given the vast reach already of what it calls the "Islamic State."
While it's been widely reviled internationally, ISIS has managed to attract some support among Muslims and drawn foreign fighters, like the masked man with an apparent British accent who took part in Foley's beheading.
Even without specific threats in the West, ISIS' track record in Syria and Iraq -- where it was known to massacre minorities, forcefully institute Sharia law and stage executions and stonings -- suggests it may be capable of anything. Cameron said the group poses a "greater and deeper" threat than Britain has known before.
Cameron said military force is among the tools that can be used against ISIS, while adding that aid, diplomacy and political influence should also be part of Britain's response.
The Prime Minister vowed Friday he would soon announce plans to stop would-be jihadists from traveling to Syria and Iraq and to make it easier to take their passports away.
Britain also needs to do more to stop current fighters from returning from the Middle East and to deal decisively with those who already have returned, he said.
UK authorities estimate that 500 Britons have gone to Syria and Iraq to fight with Islamist groups.
While the threat level just went up Friday, Britain's national policing lead for counterterrorism, Mark Rowley, said that police have been escalating their efforts to combat the jihadist threat for months. He claimed 69 arrests in the first half of 2014 for offenses ranging from funding "terrorist activity through to the preparation and/or instigation of terrorism acts and traveling abroad for terrorist training."
U.S. terror threat level
U.S. officials said Friday there were no plans to raise the United States' terror threat level.
White House spokesman Josh Earnest said he did not anticipate the threat level would rise anytime soon, and U.S. Secretary of Homeland Security Jeh Johnson said there was no specific threat against the United States.
Security was set to increase for those traveling during the U.S. Labor Day weekend, but not necessarily because of ISIS.
Transportation Security Administration spokesman Ross Feinstein said it was customary to see increased security before a holiday weekend, but it was not necessarily tied to an increased terror threat.