Any such ground operations are at least months away, U.S. officials say. The delayed response is necessary, they argue, to produce a fighting force with regional backing.

That means the undertaking will certainly fall into the next presidential administration, whether that president is the incumbent, Barack Obama, or his Republican rival, Mitt Romney.

Either will find Mali a messy and complex challenge.

Mali has long been Africa’s backwaters – undeveloped, weak, landlocked, with few binding connections to the West – and was not even an afterthought when NATO intervention in Libya helped topple Moammar Gadhafi one year ago.

Gadhafi’s collapse, however, unleashed the events that triggered what has taken place here, as thousands of nomadic Tuareg tribesmen poured back into northern Mali after years of service in Gadhafi’s army, bringing rebellion and uncounted tons of Libyan weapons.

The Tuareg rebels rapidly took control of two-thirds of Mali. The central government in southern Bamako was overthrown in a military coup by frustrated mid-ranking officers, who proved incapable of resisting the rebels. Then, Islamist militants quickly outmaneuvered the secular Tuareg rebels, pushing them aside and seizing an area the size of Texas.

And, just like that, a new extremist-led sub-state was born.

"When you started fighting in Libya, did you think of all the consequences in the region? No," complained a senior Malian security official, who asked not to be named since he was not authorized to speak to reporters.

Often described as a no-man’s land, northern Mali’s Saharan dunes may not seem like much of a prize – yet, for al Qaida-affiliated extremists, they are. Northern Mali sits along lucrative ancient trade routes that are today some of the busiest illicit highways for drugs, arms and smugglers. Northern Mali’s amorphous and rough terrain make it a logistical and tactical nightmare for invaders.

Reports abound of extremists using money from hostage ransoms and the drug trade to recruit more and more young men into their ranks in preparations to defend their strongholds. The north’s economy, shattered by the war, is picking back up again as residents return, more willing to accept occupation at home than life as an urban refugee.

At one refugee camp here at the country’s dividing line, no new arrivals could be found from the past two months. The camp had shrunk significantly since the beginning of the crisis in April, said local officials and refugees. Buses are now packed heading north, and almost empty heading south.

The decision is splitting families. Hawa Dicko fled the north at the beginning of the rebellion, but she still returns to visit family – but always leaves again. "I will stay here until the war ends," she vowed, saying she refuses to live under the gender segregation imposed by the Islamists, effectively barring women from public life.

But her twin sister and her sister’s husband have decided to return home, as has another brother-in-law.

"We have to expect that people from the north who have grown up in the north are at some point not going to want to live in refugee camps," said the U.S. diplomat.

Al Qaida-linked groups have long had a presence in northern Mali, but never before have they wielded such territorial control.