The head of the US Central Intelligence Agency has said he is not optimistic about the future of Syria remaining one country.

John Brennan’s comments are a rare public acknowledgement by a senior US official that Syria may not survive a five-year civil war in its current state.

“I don’t know whether or not Syria can be put back together again,” he said on Friday at the annual Aspen Security Forum in Colorado.

“There’s been so much blood spilled, I don’t know if we’re going to be able to get back to [a unified Syria] in my life time.”