The UN Security Council’s resolution to take “all necessary measures … to protect civilians and civilian populated areas under threat of attack” in Libya is a belated but very welcome intervention by the international community to try to undermine the capacity of the Gaddafi regime to destroy Libya’s uprising and murder its supporters.

The resolution paves the way not merely for a no-fly zone but for all measures short of “a foreign occupation force of any form”, meaning air strikes can be used against Gaddafi’s heavy armour, where, as with air power, he has a decided advantage over the rebels who have been pushed back to Benghazi and Tobruk.

It does not guarantee an end to the Gaddafi regime, by any means: there is hard fighting to be done by Libyans who want to throw off this vilest of regimes. But the battlefield will be much more equal, with the advantage Gaddafi has gained from his rapprochement with the West in recent years — nearly one billion Euros worth of arms sales — partially nullified.

Most of all, as the wild celebrations in Benghazi in response to the passage of the resolution show, it signals both to the rebels that they have not been forgotten by the world, and to Gaddafi that his chances of clinging to power are fading. Two days ago, his son had promised that the conflict would be over in 48 hours, but the assault on Benghazi had barely begun when the UN defied its long history of inaction and passed the resolution.

Plainly the Obama Administration has undergone a change of heart, suddenly ramping up its support for action over the last 48 hours, plainly unnerved by the speed with which Gaddafi was pushing the rebels back, opening up the possibility of mass slaughter if Benghazi was recaptured. It was a belated change of direction — counter-productively late, as a No Fly Zone imposed two weeks ago may well have forestalled Gaddafi’s push — but nonetheless should be acknowledged as a display of decisiveness from an administration so far uncertain about how to handle recent events in the Middle East.

The passage of the resolution also reflects credit on Kevin Rudd. He was among the earliest foreign ministers to demand a no-fly zone in Libya, and earned the usual reward of those who defy the foreign policy establishment — background leaking designed to discredit him. It turns out he was right.