Sunny Ugoh, a spokesman for the Economic Community of West African States, denied that the organization hadn’t received commitments for the troops. "Yes, they are all pledged, but I don’t want to get into the details," he said.

Signs have been building that the African force would face significant hurdles. The government of Nigeria, which is expected to form the backbone of the mission, has said it will send only 600 troops, according to news reports there. Other countries have indicated they’ll send only medical units or military police. Some West African nations speak French, others English.

Many analysts doubt that 3,300 troops are enough to challenge the desert-hardened rebels, who easily routed the ragged Malian army in April. According to the U.N., the Islamist-led rebels have 3,000 "core" fighters and are recruiting more.

U.S. officials have been bearish on prospects of intervention for months. The assistant secretary of state for African affairs, Johnnie Carson, told Congress over the summer that a military intervention in northern Mali by the West African organization is "ill-advised and not feasible." The U.S. was engaging with Mali’s neighbors to contain the terrorist elements within the country’s borders until the Malian political crisis in the south was resolved, Carson said at the time.

That attitude has gradually shifted, with Army Gen. Carter Ham, the commander of U.S. Africa Command, telling the London-based research center Chatham House last week that although the African intervention plan needed more work, its framework was sound.

But U.S. policy also is knotted by American laws: Because Mali’s current government owes its existence to a coup by unhappy army officers last spring, the U.S. is barred from giving any aid to the country’s military or government until democratic governance is restored. With Washington’s demands for new elections in Mali even without northern participation widely rebuked, those restrictions are unlikely to be lifted soon.