Syria: We must act now against Assad, says Cameron The Prime Minister made his case for military intervention against a backdrop of widespread public scepticism about the use of British military force in yet another foreign conflict, in the wake of those in Iraq, Afghanistan and Libya. On Tuesday night, though, there appeared to be growing political consensus that British involvement may be necessary. Mr Cameron said: "What we have seen in Syria are appalling scenes of death and suffering because of the use of chemical weapons by the Assad regime, and I don't believe we can let that stand." William Hague, the Foreign Secretary, said that Britain's national security would be at risk if we failed to respond. Writing in Wednesday's Daily Telegraph he warns: "We must proceed in a careful and thoughtful way. But we cannot permit our own security to be undermined by the creeping normalisation of the use of weapons that the world has spent decades trying to control and eradicate. Nick Clegg, the Deputy Prime Minister, gave his full backing to Mr Cameron, saying: "The murder of innocent men, women and children through the use of chemical weapons is a repugnant crime and a flagrant abuse of international law. If we stand idly by we set a very dangerous precedent indeed. Senior Tories are also privately hopeful that Ed Miliband, the Labour leader, will ultimately back a motion for military action. The Prime Minister issued an impassioned plea for support from his colleagues after announcing that Parliament would be recalled on Thursday to debate how Britain should respond to the crisis. MPs will be given a vote on the use of military action and the Government will respect the result, sources said. The planned intervention is understood to involve a weekend offensive. However, Downing Street indicated that Mr Cameron would retain the right to act swiftly and without the need to consult Parliament if circumstances required an urgent decision to approve the use of military force sooner. A grab taken from a video uploaded on YouTube by Moadamiyet al-Sham media centre allegedly shows a Syrian man pointing to a bullet hole in one of the vehicles used by the United Nations (UN) arms experts during their inspection visit to the Moadamiyet al-Sham suburb of Damascus on August 26 (AFP/Getty Images) The Prime Minister made his first public statement on the proposed UK response to the atrocities in Syria on another day of developments in the crisis: The Syrian regime warned that it would "defend" itself in ways that would "surprise" the world if the West used force. The White House prepared to release a final declassified version of the intelligence report it says will justify military strikes by giving overwhelming evidence that Assad's forces were responsible for the chemical attack. Russia sent a plane into Syria to evacuate its citizens as Dmitry Rogozin, Russia's deputy prime minister, accused the West of behaving towards the Islamic world "like a monkey with a grenade." The Archbishop of Canterbury, the Most Rev Justin Welby, told The Telegraph that MPs should not "rush to judgment" over military action, warning it could have "unforeseeable ramifications across the whole Arab and Muslim world." Some of Britain's most senior military figures, including Gen Sir David Richards, a former chief of the defence staff, and Lord Dannatt, a former head of the Army, warned against taking action. MPs expressed concern that intervening in Syria could result in a repeat of Britain's involvement in Iraq. Those developments came as preparations for a UK and US-led attack intensified, with British and American military and intelligence chiefs preparing plans for a possible 48-hour barrage of cruise missiles as early as Friday or Saturday. Chuck Hagel, the US defence secretary, declared that American "assets" had been moved into position and that his forces were "ready to go" on President Obama's order. Downing Street said the Armed Forces were making "contingency plans" that would on Wednesday be presented to the National Security Council meeting of senior Cabinet ministers, intelligence chiefs and military commanders. However, the Prime Minister is facing calls to publish the Attorney General's legal advice on how military strikes against the Assad regime would be justified under international law, in the absence of a United Nations resolution. Conservative MPs were preparing to defy Mr Cameron's orders to return to Westminster to vote for military action in the Commons on Thursday, while Labour warned it would be prepared to whip its MPs to oppose the strikes. Mr Miliband, who was called into No 10 to be personally briefed on the evolving security crisis by Mr Cameron, suggested on Thursday night that he remained unconvinced of the case for military force. He said Labour would consider supporting international action only if it was legal and specifically limited to deterring the future use of chemical weapons. On Tuesday the Prime Minister held a fresh round of talks with world leaders in an effort to secure the backing of Turkey, Denmark, Holland and Italy. Mr Clegg spoke to the US vice president, Joe Biden as Britain and America agreed to continue to "consult closely." British sources said Washington was "planning" for possible missile strikes as early as Friday or Saturday. A grab taken from a video uploaded on YouTube by Moadamiyet al-Sham media centre allegedly shows the United Nations (UN) arms experts convoy leaving Damascus' Moadamiyet al-Sham suburb following an inspection visit on August 26 (AFP/Getty Images) However, unless an emergency arises, no action will be taken before MPs have voted. Although Thursday's vote is not binding, Mr Cameron "is clear that the Government will respect Parliament's view," the source said. Walid al-Muallem, the Syrian foreign minister, used a televised press conference to deny that government forces had carried out the poison gas attack last Wednesday and accused America and Britain of preparing to go to war on the basis of "lies." "We have the means to defend ourselves and we will surprise everyone," he said. We will defend ourselves using all means available. Notes of caution against British intervention were also sounded by senior military leaders. Gen Sir David Richards, a former chief of the defence staff, said: "The scale of involvement to make a decisive difference in Syria would be so huge that it is something that we, at the moment, cannot sensibly contemplate." Sir Menzies Campbell, the former Liberal Democrat leader, said he was anxious about the prospects of missile strikes. We have recent experience of that in relation to the declaration of war against Saddam Hussein. Look at the way that turned out," he said. The Prime Minister will chair a meeting of the National Security Council in Downing Street on Wednesday. The body, which includes the Foreign Secretary, the Defence Secretary, the heads of the intelligence services and military chiefs, will agree on a final recommendation on how to respond to the chemical attack. The plan will then be presented to Cabinet on Thursday morning before MPs gather in the Commons for the vote.