Prime Minister David Cameron said on 26 November that Britain should join air strikes against the Islamic State (Isis) in Syria, arguing the UK should not outsource its security to allies.
Cameron, who lost a vote on air strikes against Syrian President Bashar al-Assad's forces in 2013, needs to persuade several lawmakers in his own Conservative Party and some in the opposition Labour Party to back his cause if he is to win parliament's backing for military action.
"If we believe that action can help protect us, then with our allies we should be part of that action not standing aside from it," Cameron said. "And from this moral point comes a fundamental question: If we won't action now, when our friend and ally France has been struck in this way, then our allies in the world can be forgiven for asking 'If not now, when?'
"But Mr Speaker, we do face a fundamental threat to our security. We can't wait for a political transition; we have to hit these terrorists in their heartlands right now. And we must not shirk our responsibility for security or hand it to others. Mr Speaker, throughout our history the United Kingdom has stood up to defend our values and our way of life. We can and we must do so again and I commend this statement to the house."
Cameron confirmed, after a series of questions from opposition leader Jeremy Corbyn, that British boots would not hit Syrian soil.
"Let me give an assurance, we are not deploying British combat forces, we are not going to deploy British combat forces," the prime minister said. "We think actually the presence of western boots on the ground in that way would be counter-productive. That is one of the things we have all, I think collectively across the house learnt from previous conflicts and we don't want to make that mistake again."
Lawmakers will have a few days to mull over Cameron's case and a vote could take place early next week.