A call for action from the Arab League sounds like a contradiction in terms, given the 22-member organisation's reputation for ineffectiveness.
Its request for the UN Security Council to impose a no-fly zone over Libya may come too little, too late for the Libyan rebels whose military weakness has been underlined in the past few days by defeats in the east and west of the country.
For the first time, Colonel Muammar Gaddafi is beginning to look as if he may survive and even crush the rebellion against him that seemed close to victory two weeks ago. A no-fly zone, even if was imposed, would be unlikely at this stage to stop his counter-attacks, which depend more on tanks and artillery than airpower.
Such a no-fly zone is, in any case, far from being inevitable since the US may not support such a resolution at the Security Council. When the idea was first mooted, US Defence Secretary Robert Gates said setting up such a zone would in practice be the opening act of a war because the US would have to attack Libyan air defences. To turn the tide in the fighting, the US and its allies would probably have to do a lot more, such as using its planes to prevent the pro-Gaddafi units advancing on Benghazi.
The Libyan government has also had some luck in that the Japanese earthquake has shifted international media attention away from Libya for the first time in three weeks. Political pressure against Gaddafi and in favour of the rebels is likely to subside once it is no longer in the spotlight. If, however, his forces engage in well-publicised massacres in recaptured towns, then he might, once again, risk international intervention.
The first military successes of the regime are also serving to underline that the rebel leadership, supposedly grouped in the National Transition Council, has remained fragmented and unable to weld enthusiastic but untrained volunteers into an effective military force. The loss of Zawiya, west of Tripoli, and the oil ports of Ras Lanuf and Brega to the south of Benghazi, show that lightly armed militia face inevitable defeat when assaulted by armour backed by artillery.
It remains a mystery of the uprising why the estimated 6,000 troops, whose defection led to the rebels seizing eastern Libya, have not been seen in the front line. Their commanders are not united and appear to be hedging their bets by staying out of the fighting.
Much will depend on whether or not pro-Gaddafi troops can keep up the momentum of their initial advance and move on Benghazi. If they do, then events may outpace action by the US, Nato and European leaders. If, on the other hand, the rebels hold on to the east of Libya, then the broadly-based but confused international backing for them may jell and lead to action.
The significance of the move by the Arab League is that it gives US or Nato a cloak of Arab support and intervention will not look like a rerun of Iraq. It underlines the degree to which Gaddafi is isolated internationally, though he will present a no fly-zone or any other action against him, as an imperialist venture to be resisted.
The lesson of the Libyan rebellion so far is that both Gaddafi and his enemies command few forces they can wholly rely on. It will not take much to tip the balance, but a no-fly zone may no longer be enough to save the rebels.