By ITV News Washington Correspondent Robert Moore
I think the Americans see a perfect storm brewing in the Middle East - really a war within a war - as various Jihadi groups fight each other for relevance and supremacy.
The concern in the US for counter-terrorism groups is that either Isis or its rivals in terms of al-Qaeda affiliates might seek to gain notoriety and new followers by attacking the US home land.
I don't believe there's a specific threat the US intelligence has intercepted.
But there is alarm here that some of these groups have gained deep technical knowledge of bomb-making as well as access to European followers - those are individuals who may not need a US visa and who with relative ease could get onboard a US-bound airliner.
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Although Israel was widely believed to have been behind the airstrike on September 6, it has never before commented publicly on it.
Top temperatures of 12 Celsius (54 F).
Sarah Sanders, the White House spokeswoman, acknowledged that the attack wasn’t even mentioned in the phone call.