WASHINGTON – Britain’s Parliament has been recalled once again to hold a crisis vote on whether to authorize military intervention in another Middle East conflict.Framed by opposition party members as history repeating itself, Thursday’s meeting of Parliament has already been compared to the drumroll that preceded action against Libya in 2011 and Iraq in 2003.But Western military campaigns in Iraq and Libya cannot reasonably be compared to the action that appears imminent against the regime of Syria’s embattled president, Bashar Assad.The specter of weapons of mass destruction motivated Western allies to act in Iraq preemptively, unilaterally and without due diligence. The premise of the war was that Iraq’s leader, Saddam Hussein, could not be trusted to acquire WMD. He had used them years before, in Halabjah in 1988.But the international community was not in agreement that Hussein was pursuing WMD capability, much less in accord on the progress of the development of such programs, as US intelligence alleged.In the case of Syria, however, no country – not even Assad’s allies – question that the regime has stockpiled massive amounts of chemical weapons.Assad’s government admitted it possesses these weapons in 2012. Syria has the largest stock of sarin in the region, and historically, Russia aided in the development of that program.The point of drawing a redline on the pursuit of WMD – such as was done to justify the invasion of Iraq – is to avoid a much deeper redline: the use of WMD, as was evidently crossed last week in the Damascus suburb of Ghouta.Even Iran’s leadership, closely allied with Assad, has admitted that chemical weapons were used last week in Syria to devastating effect. The question now is only of culpability, and to that end, there exists no credible evidence that Syria’s fractured rebel forces could make, much less deliver, chemical weapons on a massive scale.The issue is not a matter of intelligence. On Syria, it is a matter of will – both of the people in the US and Britain and of their leaders, reluctant to take on the costs of yet another war.And yet, again in contrast with Iraq, a full declaration of war by the West on Syria is simply not in the cards.“This is quite different to that ‘boots on the ground’ invasion of another country,” Nick Clegg, UK deputy prime minister, said on Tuesday. Clegg’s political party, the Liberal Democrats, staunchly opposed the 2003 invasion of Iraq.Western intervention in Libya may be a more appropriate case study when examining the looming attack on Syria, but still has significant differences in the details that matter.Syria is a country a third the geographic size of Libya, with three times the population.Assad has stocked and used chemical weapons, whereas Libyan leader Muammar Gaddafi had not at the time.And Syria’s civil war is burdened by deep sectarian rivalries, while the Libyan conflict was much simpler: rebels were united in their fight to overthrow a dictator.“In the case of Libya, the purpose of military intervention was to win the war for the rebels,” said Gary Samore, executive director of research at the Belfer Center at Harvard.The purpose of intervention in Syria, at this point, will not be to turn the tide of the war against Assad’s favor. It will be to underline a fundamental international norm set forth by the West: the world will not tolerate the use of WMD. Sovereignty is a responsibility, they will assert, and not a right.Samore says that Kosovo, not Libya or Iraq, provides the best template for comparison to the Syrian crisis. And indeed, the US administration has been studying NATO’s 1999 intervention in the Yugoslav conflict closely in recent days.“The big differences with Libya and Iraq are the facts on the ground,” Samore said. “But it’s based fundamentally on the principle that outside actors can intervene in a local conflict against a government, if that government has failed to protect its people.”Former UK prime minister Tony Blair was ridiculed for coming out in favor of Western action against Syria’s President Bashar Assad on Monday. Polls and local press coverage suggest that much of the British public is still bitter over being misled into the Iraq war under his leadership.