David Cameron is to present his case to the Commons later for the UK launching air strikes against the so-called Islamic State group in Syria.
The prime minister will urge MPs to back military action as he sets out a “comprehensive strategy” to tackle IS.
He will warn of the threat posed by the militant group to the UK and say the country should not “sub-contract its security” to others.
A Commons vote is expected within weeks on whether to authorise air strikes.
Mr Cameron is expected to tell MPs: “Decisions to use force are not to be taken lightly.
“It is right that Parliament, on behalf of the people, asks difficult questions and holds the government to account.”
Rebellion?
He will respond to a recent Foreign Affairs Committee report, which set out a number of tests it said should be met before air strikes were considered.
The committee said there should be no military intervention without a “coherent international strategy” on tackling IS and ending Syria’s civil war.
Mr Cameron will need to convince enough MPs from other parties to back his case in order to offset any Conservative rebels.
Labour leader Jeremy Corbyn is under pressure to offer his MPs a free vote.

Mr Corbyn has indicated his opposition to intervention, but some of his MPs are likely to back the move.
The Labour leader is hoping his shadow cabinet can reach a “collective view” before the day of the vote.
MPs rejected strikes against Syrian government forces in a 2013 vote, but have since authorised action against IS in Iraq.
The government argues it is “illogical” to restrict action to Iraq as IS does not recognise the border between the countries.
It has said it will call a vote on targeting the group, which it refers to as Isil, only when it is sure to win.

BBC