The British unwillingness or political division regarding a military intervention in Syria is closely linked to the United Kingdom's previous experiences, notably during Iraq and Afghanistan invasions. Both did not really contribute to any strategic achievements, they were rather considered as a major failure to Britain.
Indeed, Blair's intervention in Iraq and Afghanistan stemmed from his belief that in certain circumstances one must break or disregard international law in order to pursue the greater good for the sake of humanity. Tony Blair settled this doctrine during his Chicago speech; he asserted that powerful countries such as Britain should intervene in foreign affairs because "Acts of genocide can never be a purely internal matter. When oppression produces massive flows of refugees which unsettle neighbouring countries then they can properly be described as 'threats to international peace and security'. When regimes are based on minority rule they lose legitimacy". By putting some major considerations to his doctrine, Blair justified his future military interventions in other countries such as Afghanistan and Iraq. The war in Afghanistan began on October 7, 2001 when British troops in coordination with American, French, Australian, and Canadian forces launched an attack aiming to destroy the terrorist organization Al Qaeda. This war was led in response to the terrorist attacks of 9 September 2001 on the US. However, the war was not a great success, for instance, according to the British Ministry of Defense, the Afghanistan war has taken the lives of "453 British forces personnel or MOD civilians" and the fighting still continues 13 years later. Similarly, the Iraqi war was conducted on March 20, 2003, after Afghanistan attack, which increased the debate on the legitimacy of military intervention. Although the two wars were linked, the Iraq War was accelerated by fear that the president of Iraq, Saddam Hussein, was in possession of weapons of mass destruction. Nonetheless, it was not long after the invasion it became evident that there were no WMDs inside Iraq as pretended. This was a major setback to the British government because it was their main argument for going to war against Iraq. At the end of the six-year war in Iraq, the British military casualties were 179. It is noteworthy also that the two wars have cost Britain a large amount, which raised doubts on the financial ability of Britain to cope with a new and more challenging and risky intervention in Syria.
Therefore, the British opposition or Labour party under the leadership of Ed Miliband but also some Tory and Lib Dem MPs were influenced by many factors that must be taken into account as to why they blocked Britain's use of the military option to end violence in Syria. Indeed the aftermath of Iraq and Afghanistan invasions have played a crucial role, hence Britain seems less interested in adopting an active or engaged foreign policy that involves a military intervention. The post Iraq war investigations and the rise of British public discontent compelled the Labour party in the aftermath to closely review its foreign policy. Faced with growing criticism even within his party, the Labour Prime Minister Tony Blair did also resign in 27 June 2007, thus the Iraq war was the fundamental reason, which put an end to Blair's premiership. Moreover, after coming to power in 11 May 2010, the British coalition government attempted to pursue a cautious foreign policy, "suggesting that the New Labour governments had been too free with their use of military force as a policy tool" and a means to achieve political purposes. Indeed, Blair's intervention in Iraq was accused of lacking accuracy and not being well-grounded on evident arguments, notably after the discovery of Saddam Hussein's non-possession of WMDs. This misinformation claimed the lives of thousands of people from both sides - Iraq and Britain - and did also contribute to some extent to the deterioration of British relations in the Arab world. This helps to understand one of the reasons why, even after nearly three years of violent civil war, there has not been military intervention in Syria. When Blair decided to invade Iraq, he had neglected the European Union, the United Nation, and international law. Thus, the Labour party today is paying particular attention to their approach regarding the Syrian conflict; the British system is opting for a deeply revisionist foreign policy in order to avoid the mistakes of the past. Broadly speaking, the British stance, which consists of not directly intervening in the Syrian civil war that has been going on for over three years is without doubts in response to the discontent and mistakes committed during both the Iraq and Afghanistan wars. There has been a clear shift away from the principle of liberal intervention adopted by Tony Blair and expressed in both the British foreign policy and the minds of British people. The war left the latter with little desire for new adventures and little national and financial power to launch wars. It did also spread skepticism regarding the notion that the United Kingdom can play a good transformative role in conflicts.