The killing of James Foley by Isis caused an upsurge of international revulsion and condemnation with harsh words from the US defence secretary and others. But the Obama administration is trying hard not to be sucked into a war that could be more serious than the US invasion and occupation of Iraq between 2003 and 2011. What Isis showed by Foley's very public murder is that it will always raise the stakes in any confrontation with the US and anybody else. It trumped America's reassuring portrayal of the recapture of Mosul Dam by the Kurds aided by US air strikes as a sign that Isis could be defeated.