British Prime Minister David Cameron on Thursday argued his case for Britian to join air strikes operation in Syria against ISIS in the aftermath of the deadly Paris attacks that left 130 people dead.
Arguing for his case, the British PM said, "If we won't act now, when our friend and ally France has been struck in this way, then our friends and allies can be forgiven for asking: If not now, when?"
With signs of opposition against this move weakening, a vote is expected to pass in Westminster Abbey as early as next week.
Cameron argued there was a legal basis for intervention for self-defence because of the threat posed by ISIS terrorists at home, and said Britain should not "sub-contract" its security to allies.
In a statement to the Commons, Mr Cameron admitted that IS - also known as Isis, Isil and Daesh - could not be defeated by airstrikes alone. But he argued it was a key part of a wider "comprehensive" strategy to deal with the threat.
Mr Cameron set out his detailed case for extending airstrikes to Syria in a 32-page response to the Foreign Affairs Committee report.
"We have to deny a safe haven for ISIS in Syria. The longer ISIS is allowed to grow in Syria, the greater the threat it will pose," he said in a written statement on the issue, using another word for ISIS.
Cameron called for "patience and persistence" and outlined a seven-point strategy for Syria, including diplomatic and humanitarian efforts and planning for what will happen if President Bashar al-Assad falls.
Cameron is expected to call a vote in parliament on the issue before recess begins on December 17.
This will come two years after a previous vote for military action in Syria failed after the main opposition Labour Party voted against.
Labour's anti-war leader Jeremy Corbyn is against any military action but Cameron appears increasingly confident he can get enough support from Labour MPs to pass the vote, particularly after last week's UN Security Council resolution authorising countries to "take all necessary measures" against ISIS.
Mr Corbyn stopped short of saying he would order his MPs to oppose military action in a vote - which could take place as early as next week.
But he warned of "unintended consequences" if Britain got involved in military action in Syria in the same way it had in Iraq and Afghanistan.
The Scottish National Party's leader in Westminster Angus Robertson said that his party's MPs will not vote for air strikes in Syria unless they are convinced that there is effective ground support and a fully-costed plan for post-war reconstruction.
(With agencies input)