In 2003, Tony Blair made the now infamous case for the Iraq war. Despite vocal opposition from within his own party and the Lib Dems, he enjoyed the overwhelming support of Parliament. Then Conservative leader Iain Duncan Smith backed the war and so did all but 15 Tory MPs. Militaristic foreign policy bought the political elite together. The atmosphere now could not be more different. As a consensus grows around Britain’s failures in Iraq and Afghanistan, MPs are becoming increasingly sceptical of interventionism. This is epitomised by the current split in opinion over arming the Syrian rebels.
Paul Flynn, a Labour MP who campaigned against the Iraq war, told me: "The anti-war sentiment is deep-seated among all parties. Two futile wars in Iraq and Afghanistan have cost us dearly in blood and treasure."
His cynicism towards Britain’s role in the Middle East is shared by others in Parliament. Last month, Caroline Lucas led a debate in the Commons on the decision to invade Iraq, ten years on from the start of the war. The overwhelming feeling among MPs was that the government made the wrong decision.
Growing scepticism towards interventionism might also reflect Britain’s role in Libya. The 2011 action prompted little opposition (just 13 MPs  voted against it) and Ed Miliband actually encouraged the government to act more quickly. Britain was better placed to intervene in Libya than in Syria; the Gaddafi regime was weaker than Assad’s and the atrocities were, at the time, seen as more 'one-sided'. The main objective of the intervention was achieved and Gaddafi was overthrown, but not all is well in post-intervention Libya. Parts of the country, particularly Benghazi, are still plagued with political violence. Many who fled at the height of the conflict are scared to return. Last month, the Libya Herald reported that 650 Libyans had refused to leave a refugee camp in Tunisia. Such reports have contributed towards the current anti-war sentiment, with MPs thinking twice before allowing Britain to support rebels in another state.
This growing movement has left David Cameron and William Hague with few allies in their attempt to argue for greater involvement in Syria. In 2003, Blair faced significant opposition when he made the case for invading Iraq, most notably from Robin Cook, who resigned from the cabinet. But he was still able to win more support for a full-scale invasion than Cameron can for arming a rebel group.
Unlikely alliances are being formed in opposition to militarism. Boris Johnson is not known for toeing the party line, but he is seldom so defiantly on the side of Ed Miliband. Last month, he warned  that weapons might end up in the hands of "al-Qaeda thugs" after the Labour leader had claimed the government was too focused on arming the rebels. Eighty Tory MPs have signed a letter demanding a vote on the issue and the cabinet appears divided, with Nick Clegg and others publicly expressing their concerns.
Flynn told me: "Hague's demand that we should punch above our weight is clearly understood to lead to dying beyond our responsibilities and spending beyond our interests."
His own anti-interventionism no longer casts him as a rebel in his own party, as it did in 2003. A wind blowing through Westminster threatens to tear apart the political establishment as the Prime Minister’s critics find support from the most unlikely quarters. David Cameron may still push for increased British involvement in the Middle East but he is unlikely to have parliament – or even his own party – on side.