Prime Minister David Cameron has presented his case to the Commons for the UK to bomb Islamic State (IS) militants in Syria. He hopes to win MPs' support in a parliamentary vote next week. What's going on in Syria? Syria has been embroiled in a bloody armed conflict for nearly five years. More than 250,000 Syrians have been killed, and 11 million made homeless. What started as pro-democracy Arab Spring protests in 2011 spiralled into a civil war between President Bashar al-Assad's government forces and opposition supporters. In the chaos, jihadist group Islamic State moved in over the border from Iraq and claimed territory. The US, Russia, France and other world powers have entered the fray, adding to the already complex web. Syria: The story of the conflict What is the UK currently doing about it? The UK has deployed air power to Iraq in the form of eight RAF Tornado aircraft, which operate out of a British base in Cyprus. The jets have carried out about 30% of coalition surveillance missions, and under 5% of coalition air strikes in Iraq - launching guided bombs or Brimstone missiles aimed at IS targets. Reaper drones, which are remotely piloted by RAF crews in the UK, have also carried out surveillance and launched missiles at IS targets in Iraq. Parliament has not approved UK air raids in Syria - however British pilots have been embedded with coalition air forces, and two British jihadists in Syria were killed by an RAF drone strike. Why is the UK bombing Islamic State in Iraq, but not Syria? In 2013, MPs voted against possible UK military action against President Assad's forces in Syria, after evidence chemical weapons were used against civilians. Just over a year later, MPs overwhelmingly approved UK air strikes in Iraq - this time specifically against IS militants. The influential Commons Foreign Affairs Committee warned against extending bombing to Syria without a "coherent international strategy". David Cameron says it makes no sense to stop at a border IS does not recognise. He has come up with a strategy for Syria to try to build support among MPs ahead of a fresh vote. Why does the UK want to extend operations to Syria? David Cameron says IS poses a terror threat to British people, and so the UK must strike "at the head of the snake" at IS headquarters in Syria. British precision weapons would greatly help the allies' campaign, he says. However, the Commons Foreign Affairs Select Committee says the UK would only have a "marginal effect" on the conflict, and risks "further reputational" damage unless it can make a clear legal case for action. Others, including Labour shadow chancellor John McDonnell, have warned against repeating mistakes of the past in Iraq and Libya, and questioned how bombing in Syria would prevent attacks from home-grown terrorists. What is David Cameron's plan? David Cameron has set out what he thinks the UK should do about the situation in Syria. It involves military, diplomatic and humanitarian action. He ruled out British "boots on the ground" - and insisted the RAF had specialist bombing capabilities that were needed by its allies. He argued there was strong legal justification on grounds of self- defence and the recent UN Security Council resolution. He also promised the UK would help deliver a government to "represent all of the Syrian people" and plan for post-conflict reconstruction. What impact would British air strikes in Syria have? A number of people, including the prime minister, have conceded that air strikes alone are not enough to defeat Islamic State. Defence think tank, the Royal United Services Institute (Rusi), has said IS will only be dislodged by "credible Arab ground forces prepared to fight block by block" through urban centres. Meanwhile the chief of the defence staff said while the UK should support its allies with air strikes, playing any "decisive role" could "add fuel to the radicalisation of Isis as an abhorrent cult". What are other countries doing? To date, US aircraft have conducted nearly all of the air strikes undertaken by the international coalition in Syria and Iraq. However, others taking part in the US-led coalition include France, Belgium, Denmark, the Netherlands, Australia, Saudi Arabia, Jordan, Qatar and Bahrain. Russia is not part of the US-led coalition. It claims to be targeting IS strongholds - however, the US fears Russia is actually targeting opponents of President Assad, who is a Russian ally. Germany is not taking part in air strikes, but has said it will do more. iFrame Where do political parties stand? While the majority of Conservative MPs would support UK military action in Syria, there are about 20 expected to oppose it. Labour is split. Leader Jeremy Corbyn is opposed to military action, but about 20 to 30 of his MPs are thought to be in favour - including members of his shadow cabinet. The SNP remains "unconvinced" and wants to see clear UN legal authorisation for air strikes. The Liberal Democrats have said they are not yet persuaded. The Greens, Plaid Cymru and UKIP are expected to vote against extending air strikes to Syria. The DUP has indicated it could vote in favour. Syria bombing: Where UK parties stand What is Islamic State? IS is a notoriously violent Islamist group which controls large parts of Syria and Iraq. It has declared its territory a caliphate - a state governed in accordance with Islamic law - under its leader Abu Bakr al-Baghdadi. What does it want? IS demands allegiance from all Muslims, rejects national borders and seeks to expand its territory. It follows its own extreme version of Sunni Islam and regards non-believers as deserving of death. How strong is IS? IS projects a powerful image, partly through propaganda and sheer brutality, and is the world's richest insurgent group. It has about 30,000 fighters but is facing daily bombing by the US-led multi-national coalition, which has vowed to destroy it. Source: BBC

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