"Operation Serval" -- the rapid French advance through Mali -- is in some ways reminiscent of the early days of the U.S. invasion of Iraq. "Mission accomplished" in short order, cities secured, no great resistance.

But although the scale of the French operation is far smaller than that in Iraq, there may be less welcome parallels in the weeks to come. The first suicide bomber has struck; jihadists have melted away.

Putting Mali back together again will be an altogether tougher job. The second phase of the French campaign -- restoring the territorial integrity of Mali -- is far more challenging than bombing Islamist hideouts, and involves complex political, social and economic dynamics.

In short order these include a Malian military with little credibility and discipline, political institutions that have atrophied, Tuareg separatism, continuing tensions between north and south (including allegations of human rights atrocities), vast uninhabited areas that could be bolt-holes for militants, and a refugee crisis.

Fighting broke out in the capital, Bamako, Friday between soldiers loyal to the president deposed last year and troops who supported the coup against him.

In addition, as the French look to scale back their presence, the African security force due to replace them is far from fully-fledged -- an uncomfortable mix of English and French-speaking contingents with different military cultures and levels of experience. A Nigerian general is in charge; his deputy is from Niger.

Of some 5,000 troops due to arrive, about 2,500 are so far on the ground -- among them Chadian, Nigerian, Burkinabe and Nigerien soldiers. But the force has no airlift capability of its own. Nor does most of it have the mobility to root out scattered pockets of resistance, although the Chadians have experience in desert warfare.

And on a broader canvas the fundamental regional problems remain as deep-seated as ever. As a senior national security official in the Obama Administration put it recently: "What we're seeing across North Africa and parts of the Middle East is an extremist threat that is fueled by the reality of porous borders, ungoverned territory, too readily available weapons, increasing collaboration among some of these groups, and, in many cases, a new government that lacks the capacity and sometimes the will to deal with the problem."

In Mali's case, tick every one of those boxes.

The Vanishing Enemy

The French advance into northern Mali did not involve pitched battles with the hundreds of Islamist fighters that had occupied towns like Gao, Kidal and Timbuktu. After clashes in Konna, most opted to relinquish control of towns and disappear into the desert. There are reports that some fighters have mixed in with refugees arriving in neighboring Mauritania; and that others shaved their beards and mixed in with the general population. The Algerian military has reinforced border security to try to prevent militants crossing.

The French Defense Minister, Jean Yves Le Drian, says that "hundreds" of militants have been killed over the last month. This week French forces have pursued militants who retreated into the desert around Gao and Kidal, where intense air strikes have been reported. Some 1,000 Chadian troops began moving out of Kidal toward the wild Ifhogas mountains further north and the Algerian border. By Thursday night they had reached the last Islamist bastions close to the border -- around Aguelhok.

Some senior militants have been detained, including the man said to have organized the application of Sharia law in Timbuktu for Ansar Dine, one of three Islamist groups with a presence in northern Mali.

The unknown is how well the various jihadist groups had prepared for such a rapid retreat, whether they had rear bases and supply lines ready, and whether those places have been identified and targeted by French air power. The French aim is to cut off their lines of supply, helped by Algeria's reinforcement of its border security.

France now has as many troops in Mali as it did at the height of its commitment in Afghanistan -- and, strapped for cash, it wants to begin withdrawing some within weeks. But it has already hinted that special forces will remain for pursuit operations against what Le Drian called "residual jihadists."

"We will continue to act in the north where some terrorist havens remain," Foreign Minister Fabius told a French newspaper this week.

That will probably mean keeping bombers at the airfields in Timbuktu and Sevare.

Even so, while borders in the Sahel may appear on maps, they have little bearing on reality. There are thousands of miles of unmarked, unpatrolled frontiers across which groups can retreat and reorganize. In contrast to Algeria, the ability of the Libyan and Nigerien authorities to prevent militants crossing is limited at best.

If these groups have remained (relatively) coherent, the next stage of the battle for Mali could comprise what is euphemistically known as "assymetrical warfare" -- suicide bombings, IEDs and assassinations.

The jihadist groups present in Mali don't have a history of using IEDs, but al Qaeda in the Islamic Maghreb and the Movement for the Unity and Jihad in West Africa (MUJAO) have both used such devices in Algeria.

And MUJAO says it has planted mines around the northern towns it controlled. One has already killed four Malian soldiers. The group's spokesman, Walid Abou Sarraoui, told Radio France Internationale Thursday that the jihadists were "opening a new zone of conflict."

In Gao, a town controlled by MUJAO until recently, a suicide bomber on a motorcycle blew himself up Friday, injuring one other person.

The Intelligence Challenge

Northern Mali is larger in area than Spain and while much is open desert, the Adrar de Ifoghas mountains include networks of caves and passes. Moktar Belmoktar, whose followers carried out the attack on the Algerian gas facility at In Amenas in January, and Iyad ag Ghali -- a Tuareg and leader of Ansar Dine -- know this region in intimate detail.

Over the years, Belmoktar (who is Algerian) has used his knowledge of the region to establish a flourishing smuggling and kidnapping business that has funded weapons-buying and recruitment. His group and MUJAO are thought to have taken seven French hostages they already held into the impenetrable Ifoghas.