MPs have voted in favour of military intervention in Iraq against Islamic State (IS) militants.
The precise wording of the motion does not mean "boots on the ground" - instead, it condemns "barbaric acts" by IS militants and acknowledges Iraq's request for assistance, meaning the UK will perform airstrikes on the IS in Iraq in a joint operation with the US.
RAF aircraft are on standby in Cyprus to strike "within hours", Downing Street has said.
"This is not a threat on the far side of the world," he said.
In closing remarks, Nick Clegg added that the UK "must act" to prevent the advance of IS.
We do so mindful of the mistakes and lessons of the past, but we do so with lawful authority, with clear objectives and with the support and active participation of a broad coalition of international opinion which is saying to [IS] 'enough is enough'.