The defence secretary will open the door to RAF airstrikes against terrorist targets in Syria in a speech today.
Michael Fallon will tell MPs that a new parliament should consider afresh the case for attacking the forces of Isis or the so-called Islamic State not just in Iraq but in Syria as well.
He will insist that there is no legal barrier to British military attacks and point out that both the Canadian and Jordanian air forces have already attacked Syrian targets.
David Cameron was defeated in the Commons just under two years ago when Tory rebels joined forces with Labour to oppose airstrikes on Syrian government targets designed to deter the use of chemical weapons.
Ever since August 2013 the prime minister has said he would respect the vote.
Today the Defence Secretary will repeat Mr Cameron's assurance that no military action in Syria will be taken without another vote in the Commons but he will say that following the election it is time to reconsider the arguments.
He will point to the possibility that terrorist attacks, like the murder of up to 30 Britons in Tunisia this week, may have been planned in Raqqa in Northern Syria which is known as Isis's capital city.
Ministers would not risk losing another vote on Syria unless they knew they had the support of the Labour Party.
I understand that there has been contact between the two parties to discuss the possibility of another vote on Syrian military action in the future though nothing is expected imminently.