David Cameron lacked the "balls" to take the military action in Syria that could have prevented the rise of Isis, a former head of the armed forces has complained.
In a scathing analysis of the Prime Minister's approach, General Lord Richards of Herstmonceux said it too often seemed "more about the Notting Hill liberal agenda rather than statecraft".
Lord Richards, who was chief of the defence staff from October 2010 to July 2013, made the criticism in an interview for a biography of Mr Cameron by Sir Anthony Seldon, being serialised in the Mail on Sunday.
He revealed last year that the Prime Minister had in 2012 rejected a "coherent military strategy" to take on the regime of Syrian president Bashar al Assad which would in his view have seen the Islamic extremists "squeezed out of existence".
In the book - titled Cameron at 10: The Inside Story 2010-2015 - the ex-military chief is quoted as saying: "If they had the balls they would have gone through with it ... if they'd done what I'd argued, they wouldn't be where they are with ISIS.
"In Ukraine, as in Syria and Libya, there is a clear lack of strategy and statecraft.
"The problem is the inability to think things through. Too often it seems to be more about the Notting Hill liberal agenda rather than statecraft."