The British Parliament voted down a measure on Thursday evening that would have permitted troops to intervene in Syria, by a narrow 285-272 margin. The measure was introduced and strongly supported by Prime Minister David Cameron, who earlier in the day visited the House of Commons and asked for support for a multilateral strike against Syrian president Bashar al-Assad, for allegedly using chemical weapons against his own people.

This has serious implications for the U.S. should President Obama choose to send American troops to Syria, with the possible loss of a strong ally.

Cameron said in his remarks on Thursday afternoon, “The question before the House today is how to respond to one of the most abhorrent uses of chemical weapons in a century, slaughtering innocent men, women and children in Syria.”

The prime minister used his time earlier in the day to try and convince members that going into Syria is crucial to the region’s security, but he also tried to make a moral argument. “In the end there is no 100 percent certainty about who is responsible, you have to make a judgment. There is also no 100 percent certainty about what path of action might succeed or fail,” he said. “I think we can be as certain as possible that when we have a regime that has used chemical weapons on 14 occasions, that is most likely responsible for this large-scale attack, that if nothing is done it will conclude that it can use these weapons again and again and on a larger scale and with impunity.”

Like the U.S., leaders in the U.K. are divided on the issue of invading Syria, which was evident by the slim margin of the vote on Thursday night. Some, like Cameron, believe that attacking the Syrian regime to save lives and end what is being considered genocide is entirely necessary. Others want to avoid hasty decisions since intelligence groups are still determining whether al-Assad and his regime are in fact responsible for the attacks.

Understanding what Iraq did to public perception and what it could mean for the looming vote, Cameron aimed to convince MPs and their constituents that major governing bodies are in agreement that intervention in Syria is required. Said Cameron:

I am deeply mindful of the lessons of previous conflicts, and in particular the deep concerns in the country caused by what went wrong with the Iraq conflict in 2003. But this is not like Iraq. What we are seeing in Syria is fundamentally different. We are not invading a country. We are not searching for chemical or biological weapons. The case for ultimately supporting action is not based on a specific piece or pieces of intelligence. The fact that the Syrian government has, and has used chemical weapons is beyond doubt.

The prime minister went on to state that unlike Iraq in 2003, international groups—Europe, NATO, and the Arab League—are currently in agreement that taking action in Syria is crucial.

While Cameron ruled out acting unilaterally, his remarks and recommendations on Thursday afternoon sounded far more decisive than those of President Obama, who said in an interview on Wednesday that he hasn’t yet made a determination on how to engage in the Syrian conflict. Cameron told MPs that supporting their greatest ally, the U.S., is imperative, saying, “The President of the United States, Barack Obama, is a man who opposed the action in Iraq. No one could in any way describe him as a president who wants to involve America in more wars in the Middle East.” He expressed the opinion that Obama “profoundly believes that an important red line has been crossed in an appalling way, and that is why he supports action in this case.”

Both Cameron and Obama pledged that any intervention would not lead to another long-term conflict in the region. Cameron said on Thursday afternoon, “It is not about taking sides in the Syrian conflict, it is not about invading, it is not about regime change or even working more closely with opposition. It is about the large-scale use of chemical weapons and our response to a war crime, nothing else.” The prime minister cited a 1925 protocol prohibiting the use of chemical weapons—drafted with the help of British leaders and signed by the Syrians—as the driving force behind his urgency to intervene.

Despite his best efforts on Thursday afternoon, Cameron was unable to persuade Members of Parliament to support military intervention. Had he waited until next week, when Parliament returned from vacation, there may have been more answers regarding the outcome of the U.N. chemical weapons inspection and a more definitive answer from the Obama administration and other international allies.

Reports from the U.N. chemical weapons experts are due back after inspectors return from Syria on Saturday. Russia, a Syrian ally that has opposed U.N. Security Council resolutions that would lead to an assault on the country, is now urging Syrian officials to comply with a chemical weapons investigation.

The U.S., Britain, France, and Turkey have all agreed that these attacks seem to have been carried out by al-Assad. Russia and China have warned the West that any action could further destabilize the region. In preparation, the U.S. Navy has sent its fifth destroyer to the Mediterranean and Russia has deployed some of its own warships to the region as well.

Photo via Parliament.uk