Libya: A new phase in the conflict?
The Libyan city of Misrata, besieged by government forces since the outset of this conflict, is a symbol of the rebel forces' tenacity, and of the inadequacy of Nato's strategy.
Indeed, Misrata is fast becoming the anvil on which the Atlantic Alliance's whole policy could falter.
Western air power turned advancing Libyan government forces back from Benghazi at the outset of this campaign; a quick success story, hailed by participating countries as justification for the decision to intervene.
But now, some four weeks on, Libyan government pressure on Misrata, a city of some 300,000 people is, if anything, growing.
The claim by Human Rights Watch over the weekend that Libyan government troops were firing cluster munitions into civilian areas - denied in Tripoli - gives added urgency to the city's plight.
Air strikes around Misrata's outskirts have served to keep Col Gaddafi's troops at bay, but only just.
They have infiltrated the city, parking their armoured vehicles in among buildings, making them harder to hit without risking civilian casualties.
If anything, Misrata illustrates once again the limitations of modern air power.Maritime link
Whatever politicians may think, it cannot win conflicts on its own. It is a decisive factor but must be employed along with effective forces on the ground. That is precisely what is lacking on the rebel side in Libya.
Nato aircraft have also struck at Libyan government vessels in order to keep open the tenuous maritime access to the city.
It is this maritime link that is now the focus of discussions in New York, with urgent efforts under way to bolster the volume of humanitarian aid going into the city.
But the sea route out has also been vital for the evacuation of casualties and there are growing fears for large numbers of migrant workers who find themselves stranded in a war zone.
So in a sense one phase of this conflict is over. Colonel Gaddafi's forces have weathered the storm. His regime has not collapsed.
Nato warplanes have contributed to an enforced stalemate in the east, but the inadequacies of the rebel forces mean that they are unable to defeat their government opponents on the ground.
After a hectic series of diplomatic meetings over the past week there seems to be a general sense that something more must be done,
But what? None of the options are quick or simple:1. Nato boots on the ground
Military experts believe that a relatively limited force of well-trained western troops might make a significant difference. But Nato leaders appear unwilling to countenance the use of ground troops, constrained by the terms of UN Security Council resolution 1973 and concerns about how this would look both to Arab opinion and their own publics at home.2. Equip and train
The focus may shift to providing training for the rebel forces. Qatar for one has signalled it is willing to pay, but who exactly might provide the expertise required remains an open question.
Training takes time. What the rebel forces need badly for example are low-level commanders able to conduct basic fire and movement manoeuvres. These skills cannot be learnt, and more importantly employed, overnight.
Reports from Benghazi suggest rebel forces are already beginning to get some arms shipments, though their scale and content is unclear.3. Advice and support
Another option, linked with "equip and train" would be to have outside experts or advisers on the ground alongside rebel forces. They could provide key coordinating skills which might also increase the effectiveness of Nato air-power. But here too the question is: where would they come from?
The crisis in Misrata gives added urgency to all these questions.
The Libyan operation has already gone on for longer than many of its instigators probably imagined. At the outset the skids appeared to be under Colonel Gaddafi and his regime and one more push looked set to topple him.
That is not how things have turned out, raising questions about what exactly was known at the outset.
How resilient did people think the Gaddafi regime really was? How effective were his forces? And how much or how little was known about the rebel side's capacities?