There are two bad reasons. David Cameron and François Hollande may have different policies and politics, but they currently share the same problem. Their governments are discredited and in disarray, and each hopes that muscular leadership abroad will repair its reputation. Despite what has happened in Egypt and elsewhere, Mr Cameron feels that he played the Arab Spring with aplomb, and he wants to renew the impression. President Hollande startled himself and everyone else by his vigour in Mali and he, similarly, is now tempted by un peu de gloire. This is how small wars begin and grow. Yet neither Britain nor France could assert itself were it not for the second bad reason — a belief in Washington that anything, anywhere, that weakens Iran — Syria's main sponsor — is worth it. Without any strategy to rein in the mullahs directly, the indirect strategy of overthrowing Assad and undermining Hezbollah is all that's left — no matter the long-term consequences in the region. Israel, for understandable reasons, thinks much the same. This odd conjuncture of domestically driven and internationally condoned cluelessness is not, however, the end of the matter — because there is the Bosnia angle. Indeed, without that angle David Cameron, facing strenuous opposition in the Commons, would probably have to give up.

And he should give it up, because the parallel is false and the conclusions flawed. Evil was, indeed, rampant and unpunished 20 years ago in the Balkans. In July 1993, the late, unlamented Slobodan Milosevic announced: "I think we are on the threshold of the final solution: the main remaining question is a question of maps." They would be made in Belgrade. 

Within the shell of the old Yugoslavia, a genocidal ideology, defined by Serb intellectuals, preached by churchmen and enforced by peasant paramilitaries, sought to exterminate or "cleanse" the Bosnian Muslim population. The Muslim (Bosniak) relative majority within Bosnia was determinedly secular, moderate, rakija-imbibing, part-European and part-Balkan, led by an inexperienced elite of easygoing intellectuals. It didn't pose a threat, and it didn't stand a chance. As the years went by, and the death toll mounted, the religious factor grew. Jihadists arrived from North Africa and the Middle East. But they were not effective, they were much resented, and they have largely gone; and though Bosnia today is a failing state, its problems stem from corruption and obstruction, not zeal.

The Syrian crisis is entirely different — as different as the Middle East is from the Balkans. The ruling regime in Syria, unlike Milosevic's Greater Serbia, has no governing ideology. Its Baathism is a worn joke. It is an Alawite-dominated, clan-based system, supported by religious minorities who fear the chaos that the alternative threatens. The decisive role within the opposition is played by groups such as al-Qaeda-linked Jabhat al-Nusra. Radicalisation is not, as in Bosnia, a risk: it is an all-encompassing reality. Unlike in Bosnia, Islamism in Syria has an indigenous base. It is funded and supplied by Saudi Arabia and Qatar, which direct their support to Salafis, not to secularists. If Assad is overthrown by force, as Britain and France wish, rather than eased aside, as Russia would grudgingly concede, the Alawites, Christians, Druzes, Shias, and those Sunnis who do not accept rigorous sharia, will face expulsion, intimidation and death. For its part, the West will face a grave new threat to its interests and security. Compared with that, dysfunctional Bosnia will look like the home counties.