"Many are tired, distressed and in need food and water," said Michelet William, Mali director of the British agency Plan. "We fear our already stretched resources will not last long."

Children are being recruited in the hundreds as militant fighters for the promise of food and a small wage.

Without a quick end to fighting and substantial humanitarian aid, a generation of young Malians will remain at grave risk, imperiling the country's future.

6) A test of international will

Mali is now a test bed for the effectiveness of international action against militant Islam in Africa -- action that brings together very different capabilities and cultures and that has an ill-defined goal.

Much depends on how groups like Ansar Dine and others respond to the offensive. If the militants scatter into the desert and Malian troops can reclaim the main towns, partial victory can be claimed. But if they hunker down and mix with civilians -- much as clans in Mogadishu did in 1992 -- France could find itself in an ugly war of occupation and suicide bombings, with insufficient troops (2,500 spread thin over a huge area) to provide security.

This "would raise the political costs of the French bombing campaign, dragging the intervention into urban warfare that neither France, the U.S. nor Algeria would be willing to lead with boots on the ground, and leaving Mali's fractious military exposed," according to Phillippe de Pontet of Eurasia Group.

The United States has made clear it cannot help train the Malian army until a legitimately elected government is in place, but it will provide satellite intelligence and intercepts. France has no viable drone capacity of its own.

The role of the African force and its capabilities are unknown factors. Diplomats expect some 3,300 troops from seven or eight countries belonging to the regional grouping known as ECOWAS (the Economic Community Of West African States) to arrive in Mali over the next week or so. The largest contingent will be from Nigeria, and the force will have a Nigerian commander.

They will need airlift help -- which has been promised by the United Kingdom, Belgium and Germany, and in which the United States conceivably could participate -- and are likely to be deployed in a holding role while French and Malian forces push north.

But their ability to work together and fight, should Ansar Dine militants somehow evade the Franco-Malian advance, is very much in question. They have not trained together, and they have different structures and languages. In addition, some contingents will be no more than a token force of 100 men.

This is an ad hoc "coalition of the semi-willing." Some French officials have begun grumbling that other European states are doing too little.

Even if Ansar Dine and other jihadist groups can be broken up, Mali's military and its political institutions have been shredded by the chaos of the past year, and its population is debilitated. The "Tuareg question" remains unsolved, with southerners now even more hostile to Tuareg separatism.

Many MNLA fighters are said to have fled west into Mauritania rather than get caught up in the showdown between the French and the rebels.

The French may profess satisfaction at scattering Ansar Dine, thanks to months of painstakingly compiled intelligence on the group's bases. President Hollande has pledged French forces won't leave until Mali has security, legitimate authorities, an electoral process and no more terrorism.

But these are early days in the campaign dubbed by the French military Operation Serval. The serval is an agile desert cat. But it is also an endangered species.