As Prime Minister David Cameron sets out his case for British jets and drones to strike so-called Islamic State targets in Syria, ITV News looks at why and how Britain may get involved - and some of the objections.
Why should the UK get involved in Syria raids?
David Cameron has argued that the UK's "world-leading military capabilities" could contribute significantly to the effort to destroy the militants, and a demonstration of international unity is required following recent terror attacks.
The Prime Minister also says raids would counter the "direct threat" of attacks on the UK by IS militants.
What would British air strikes in Syria involve?
- The RAF is already involved in the coalition airstrikes against so-called Islamic State targets - but are currently strictly limited to raids on Iraqi territory.
- The Prime Minister wants British raids to hit the city of Raqqa, the capital of the self-styled Caliphate and the heart of IS terror operations.
- Opening up the mission to Syria means that RAF Tornado bombers and their weapons can be put to devastating use against IS strongholds in the war-torn country.
- It will also give the RAF more flexibility to attack targets across a border that the jihadists don't recognise - putting further stresses on their infrastructure and command.
- UK operations would give moderate rebels in Syria "breathing space" to prepare for ground assaults against IS.
- The Prime Minister insists that there would be no British "boots on the ground" inside Syria, but it's not clear if this statement includes special forces.
What units and equipment would be deployed?
- Tornados from 12 Bomber Squadron equipped are the spearhead of Britain's military operation against IS in Iraq and would fly likely step up raids if a vote passes.
- Bombers from 12 Squadron are equipped with Brimstone missiles - a highly accurate 'fire and forget' anti-armour weapon.
- As the RAF has a very limited number of aircraft suitable for this kind of operation, it's not clear if any more warplanes could be deployed.
- Drones and manned surveillance provide up-to-date images and reports on IS to coalition forces already.
- The Tactical Imagery Wing at RAF Akrotiri will likely contribute to the anti-IS operation further.
What are the objections to air strikes in Syria?
The Scottish National Party will not vote to back UK air strikes in Syriabecause "key questions" remained unanswered, the party's Westminster leader Angus Robertson has said.
Other critics are worried that the operation could suffer from "mission creep" and escalate out of control, resulting in a costly ground conflict with IS - a scenario the militants would welcome.
Labour leader Jeremy Corbyn warned of "unintended consequences"
A recent report from the Royal United Services Institute says, rather awkwardly, that RAF bombing runs wouldn't make much difference to the effort against IS in Syria.
The RUSI report also adds: "The primary result of a parliamentary endorsement, therefore, would be symbolic, reassuring the UK’s allies that it had re-established its strategic nerve after the government’s unexpected defeat in 2013."