"This is going to be a mission that will take not just months but years, but I believe we have to be prepared for that commitment," the prime minister said. "We should not expect this to happen quickly. The hallmarks of this campaign will be patience and persistence, not shock and awe." While lawmakers are expected to approve the move, many questioned why Britain was not also joining military strikes on Syria. The debate has also evoked memories of Britain's role in the deeply unpopular US-led invasion of Iraq in 2003 under Labour prime minister Tony Blair, which led to the death of 179 British personnel over six years. Six British Tornado fighter jets based in Cyprus are poised to begin raids on IS militants within days or even hours after the vote, due at 5:00 pm (1600 GMT), is passed. Britain would join the United States and France in launching targeted strikes on IS jihadists in Iraq, where they control swathes of territory, as in neighbouring Syria. Denmark, Belgium and the Netherlands are also poised to take part. It will not at this stage join US-led air strikes on Syria, and Cameron said a separate vote would be needed before that could happen. That option is not currently on the table due to a lack of consensus between Britain's main parties which would likely see the proposal defeated. The main opposition Labour party, which inflicted a humiliating defeat on Cameron last year over military action against Syrian President Bashar al-Assad, has indicated it would require a UN Security Council resolution before backing action in Syria. However, all the main parties are backing Friday's motion on air strikes in Iraq, meaning that it is almost certain to be approved.