The UK government raised its terror threat level Friday from "substantial" to "severe," the fourth highest 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," Prime Minister David Cameron said. The execution of American journalist James Foley is clear evidence that ISIS's fight in Iraq and Syria "is not some foreign conflict thousands of miles from home that we can hope to ignore," according to the UK leader.
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Ex-U.S. official notes ISIS has yet to attack outside the Middle East
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UK terror threat hiked to second-highest level due to events in Iraq, Syria
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Cameron: We can't ignore Islamist extremists after James Foley's killing
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Spokesman: U.S. has no plans now to raise its own terror threat level
Cameron said the group  poses a "greater and deeper" threat than @placeholder has ever known.
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 @placeholder's response.
That said, his focus Friday wasn't so much about what to do about @placeholder overseas as it was keeping British citizens back home safe.