Prime Minister David Cameron made a strong case for taking military action to punish the Syrian regime for using chemical weapons. Labour leader Ed Miliband said that he was willing to consider it. It took a combination of party political manoeuvring and a rebellion by Conservative isolationists to defeat the government on August 29th, ensuring that Britain would not join in any operation. The vote is already affecting the UK’s relationship with the US. It may also reduce still further Europe’s willingness to equip and train for conflicts outside its borders. It does not (yet) mean that Britain has pulled up the drawbridge, but it will make it harder for future governments to get involved in wars, even for noble causes.

The vote in the Commons did not necessarily reflect a majority against the principle of military action. Four hundred and ninety MPs voted to start a process that could lead to military action. But they were split: the government, with no support from Labour MPs, put forward one set of conditions that would have to be met; the Labour Party, with no support from the coalition’s MPs, proposed a slightly different set. Only 52 MPs voted against the use of force in any circumstances by opposing both the government and opposition proposals.

The main reason that the government lost was that 30 Conservative and 9 Liberal Democrat MPs voted against the government motion (with many others absent or not voting). There was a sense among the Conservative rebels that this was not Britain’s fight: comments included "Our job in this parliament is to look after our own people" and "The world needs to act. The world, however, does not equal the UK". There was a striking amount of criticism of the US, occasionally bordering on hostility, from some Conservatives.

A closer look at the 30 Conservative rebels is revealing: 26 of them also rebelled against the government and voted in favour of a referendum on the UK's EU membership in October 2011. In the past, many Conservative eurosceptics have favoured an Atlantic alternative of closer partnership with the US rather than the EU. There is now a significant group, however, for whom the choice is not between Europe and the open sea, but between (as they see it) the illusion of "punching above our weight" and the reality of being a medium-sized power with domestic problems to fix. Their position resembles that of the populist UK Independence Party, which – to quote their website – opposes "needless foreign adventures that don't directly affect us as a nation".

To judge from opinion polls, this scepticism about UK involvement in distant conflicts reflects the popular mood; but in the past national politicians have been more willing to ignore such sentiments in favour of maintaining Britain's status as a leading world power and defender of international norms. If the Prime Minister and Ed Miliband had been more confident that taking action was the right thing to do, they might have found it easier to agree on a motion that government and opposition could both back. As it was, the Prime Minister had no hesitation in confirming on the night of the vote that the government would abide by what he considered to be the will of Parliament: Britain would not take part in any military action against Syria. Ministers have been surprisingly ready to say that there will not be another vote unless circumstances change very significantly – almost as though defeat had come as something of a relief to them. It is not clear how bad things would have to get in Syria before they would revisit the issue.

While publicly the US administration has expressed understanding for the situation, in his speech on August 30th Secretary of State John Kerry pointedly left the UK out of a list of US allies in dealing with Syria. British military staff attached to US Central Command headquarters (from which any Syria operation will be run) are reportedly being excluded from discussions. It is certainly an exaggeration to speak of the demise of the special relationship – not least because the unique intelligence relationship between the UK and US will certainly continue. But at least since the invasion of Iraq in 2003, Britain's willingness to turn up has been more important to the US than any practical military contribution it could make. If the UK loses the political will even to play a symbolic role in operations, that will certainly erode the basis of the relationship.

There is also a question of why President Obama has now decided to consult Congress before taking military action – something which clearly was not envisaged before the British vote. Was the President's position weakened by David Cameron’s defeat, so that he felt he had to give in to pressure from Congressional Republicans to offer them the same chance that British MPs had had to debate military action? Comments by White House officials suggest a degree of irritation with the British for starting down this road. If (as is possible) Obama fails to get the support of at least the House of Representatives, the administration may well put part of the blame on the British. Another CER Insight in the coming days will deal with other international implications of a possible strike on Syria.

Within Europe, the Commons vote threatens to undermine improving Franco-British ties on defence and security. David Cameron and Francois Hollande are not natural soul-mates, and Hollande did not initially share Nicolas Sarkozy's enthusiasm for defence co-operation with the UK. But Britain's willingness to provide modest logistical help in the initial stages of France's Mali operation earlier this year, and subsequent shared views on Syria (including on the question of partially lifting the EU's arms embargo to allow weapons deliveries to the opposition) had started to turn things round. This renewed alignment between the UK and France, and the embarrassment of failing to back them in Libya in 2011, seemed to be nudging Germany in the direction of supporting action in Syria (Foreign Minister Guido Westerwelle said on August 26th that if the use of chemical weapons were confirmed by UN inspectors, then Germany would "be among those who think that some consequence will have to be drawn"). After the British vote, and probably not by coincidence, Chancellor Merkel's spokesman seemed to rule out any German involvement, leaving France isolated as the only European country likely to join the US in military operations.

The British vote comes at an inconvenient time in the preparations for the December European Council discussion on European security and defence policy. The UK has been a keen promoter of increased European defence capabilities, particularly those such as strategic airlift which would enable European countries to play a more active part in expeditionary operations. But if reluctant partners believe, rightly or not, that the UK itself is losing the political will to undertake such operations, they are unlikely to respond to British pressure to spend more on such capabilities (though they may be relieved that the UK will no longer try to push them into wars at the behest of the US).

In NATO the vote may have an impact on the unresolved division between allies who believe that the alliance's main focus should be on territorial defence, and those who see the main threats to transatlantic security as global, not European, and want NATO to be able to act beyond its borders. Again, the UK's credibility as a strong supporter of an expeditionary outlook for NATO is likely to be reduced, while the position of countries like Poland (which has ruled out taking part in action against Syria and is more focused on security issues in its immediate neighbourhood) may be strengthened.

The Commons vote may turn out to have little long-term impact on the UK’s world view. Any response to Assad’s use of chemical weapons is hedged with uncertainty. If a limited strike fails to prevent the future use of nerve gas, what would the Western reaction be? What impact would a strike have on regional security? Would it destroy any hope of improving the West’s relations with the new president of Iran, making conflict more likely? Perhaps in other circumstances, with more clarity about the ramifications of action, a parliamentary majority could be found. Perhaps next time the government would do a better job of rounding up its members to vote. Perhaps next time the Labour Party, having exorcised the demons of 2003 and the decision to invade Iraq, could vote on the merits of the case when an atrocity needs to be punished.

But equally, the vote could turn out to be the signal for a strategic shift in favour of insularity. By voting – almost by accident – against even a modest military gesture, British MPs risk sending the message that in future the UK will be content to stay on the side-lines, regardless of what is happening in distant lands. For all the expressions of dismay from veteran statesmen like Tony Blair, former Foreign Secretary Sir Malcolm Rifkind and former Liberal Democrat leader Lord Ashdown, public opinion seems happy with that; and current political leaders seem disinclined to court unpopularity by reiterating the case for interventionism. For a country with global economic and security interests, that is a risky position to take, and a bad example to set.

Ian Bond is director of foreign policy at the Centre for European Reform.