The ceasefire in Syria so far has been patchy, inadequate, and violated by both sides, most egregiously by the forces of President Bashar al-Assad, who have broken a pledge to withdraw from all towns and cities and bombarded districts of Homs again yesterday. But the – distinctly relative – calm has shown that a ceasefire, however imperfect, is an improvement on the free-for-all that proceeded it, with the glaring imbalance of power between the regime and the opposition exacting a murderous toll.

The very small number of UN observers – six were preparing to enter Syria late yesterday, with another 20 or so on their way – only serves to underline the size of the task ahead. But the presence on Syrian territory of blue helmets at all is welcome progress. Two months ago, the UN process broke down in acrimony after a transition plan drawn up by the Arab League was vetoed by Russia and China. Britain and the United States heaped the blame on Russia, insisting that Syrian blood would be on its hands.

Even if that plan had passed, however, there can be no certainty that it could have been acted upon. Mr Assad had rejected it. There was no alternative diplomatic process and no basis for even the degree of intervention currently agreed. It may be that the difference between then and now is that Russia and China were so shocked by the mounting bloodshed that they reversed tracks. But the unanimous Security Council vote at the weekend to dispatch observers also follows much more careful diplomatic preparation, under the auspices of the special envoy, Kofi Annan, which included consultation in Moscow and Beijing and less overt sabre-rattling on the part of the Western powers.

The ceasefire will remain, at best, shaky. But a united international approach will be key. Mr Assad must not be given the luxury of exploiting foreign divisions to extend his time in power. Even if it does not explicitly stipulate the regime's departure, the six-point Annan programme is the best, indeed the only, plan on offer, and reducing the carnage has to be the first priority.