The United Kingdom on Friday raised to “severe” its assessment of the threat of domestic terrorism in response to the spreading grip of Islamic militants in parts of Iraq and Syria, meaning that the risk of an attack is now considered “highly likely.”
U.S. Homeland Security Secretary Jeh Johnson said that his agency and the FBI are not aware of any specific, credible threat of an attack in the United States that would prompt a higher threat level, but he echoed the deep concerns.
“I have spoken to UK Home Secretary Theresa May about these changes,” Johnson said.
He said his agency has taken several measures in recent weeks to tighten security at foreign airports with direct flights to the United States, and that the UK and other nations followed by putting “similar enhancements” in place. He did not describe them.
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“This government, in close collaboration with our international partners, has also taken a series of steps to track foreign fighters who travel in and out of Syria, and we are contemplating additional security measures concerning foreign fighters,” Johnson said. “Some of the security measures will be visible to the public and some understandably will be unseen.”
The UK’s decision lifted the terror threat level from “substantial” to “severe,” which is the second highest of five possible threat levels. BBC News reported that Prime Minister David Cameron promised new legislation to make it easier for authorities to seize passports from citizens traveling abroad to fight.
While there is no known threat to the U.S. homeland from Islamic militants known as ISIS, Johnson said that violent extremists who support the group “have demonstrated the intent and capability to target American citizens overseas.”
The Department of Homeland Security also “is mindful of the potential for homegrown violent extremism inspired by radical ideology overseas, and both through law enforcement and community outreach, we are taking steps to counter that potential threat,” he said.
The New York Times on Friday quoted intelligence sources as estimating that more than 100 Americans have fought alongside militant groups in Syria since the civil war began three years ago, with about four known to have been killed. It quoted a senior British official as stating that more than 500 citizens of the UK have joined the fight, with about half returning to England and a small number dying on the battlefield.
In his statement, Johnson said that the U.S. government “will continue to evaluate and adopt serious and prudent homeland security measures as the situation warrants.”