In a message from Washington to the heads of the Free Syrian Army groups, the US government said “you should not base your decisions on the assumption or expectation of a military intervention by us”.

The message also told the rebels that the decision on how to face the Syrian army’s military action was up to them.

“We in the United States government understand the difficult conditions you are facing and still advise the Russians and the Syrian regime not to undertake a military measure that violates the zone,” the message added.