Defence secretary Michael Fallon will make a statement to the House of Commons on Thursday on the threat posed by Isis, amid expectations that MPs will soon be asked to approve British bombing raids on the Islamic militants in Syria.
On Wednesday Fallon told BBC Radio 4’s World At One it was "illogical" that Britain was bombing Isis in Iraq but had to stop at the Syrian border. He is expected to underline this point in the Commons and say MPs should consider expanding military strikes.
Last September parliament approved RAF raids on Isis in Iraq. However MPs did not allow air strikes on targets in Syria - where the group is strongest.
There is intense speculation in Whitehall that a Commons vote on allowing strikes on Syria is imminent, but The Huffington Post understands Fallon is not expected to announce tomorrow the timing of any such vote.
The decision to restrict military strikes to Iraq came after Ed Miliband's Labour Party and several Tory backbenchers indicated they would not support bombing in Syria. Labour is reported to now be more open to expanding strikes.
Fallon told the BBC yesterday: "It is a new Parliament and I think Members of Parliament will want to think very carefully about how we best deal with Isil (Isis) and the illogicality of Isil not respecting the borderlines. They don’t differentiate between Syria and Iraq, they are establishing this evil caliphate across both countries."
"We have always been clear that Isil has to be defeated in both Syria and Iraq. We have plenty to do in Iraq; each member of the coalition is doing different things. But Isil is organised, and directed, and administered from Syria. There is an illogicality about not being able to do it."
He added: "There is no legal bar to us operating in Syria, but we don’t have the parliamentary approval for it. We don’t need it at the moment because we are playing our part in the campaign, and indeed what we do in Iraq actually frees up the United States aircraft to attack in Syria."
In August 2013 Miliband torpedoed David Cameron's plans to take military action against the regime of Syrian president Bashar al-Assad. Labour's last minute decision to block strikes infuriated Downing Street who had expected the Opposition to back the coalition's proposal for military action.