DAKAR, Senegal -- Just as Al Qaeda once sought refuge in the mountains of Tora Bora, the Islamist militants now on the run in Mali are hiding out in their own forbidding landscape, a rugged, rocky expanse in northeastern Mali that has become a symbol of the continued challenges facing the international effort to stabilize the Sahara.
Expelling the Islamist militants from Timbuktu and other northern Malian towns, as the French did swiftly last month, may have been the easy part of retaking Mali, say military officials, analysts and local fighters. Attention is now being focused on one of Africa's harshest and least-known mountain ranges, the Adrar des Ifoghas.
The French military has carried out about 20 airstrikes in recent days in those mountains, including attacks on training camps and arms depots, officials said. On Thursday, a column of soldiers from Chad, versed in desert warfare, left Kidal, a diminutive, sand-blown regional capital, to penetrate deep into the Adrar, said a spokesman for the Tuareg fighters who accompanied them.
"These mountains are extremely difficult for foreign armies," said the spokesman, Backay Ag Hamed Ahmed, of the National Movement for the Liberation of Azawad, in a telephone interview from Kidal. "The Chadians, they don't know the routes through them."
These areas of grottoes and rocky hills, long a retreat for Tuareg nomads from the region and more recently for extremists from Al Qaeda in the Islamic Maghreb, will be the scene of the critical next phase in the conflict. It will be the place where the Islamist militants are finally defeated or where they slip away to fight again, military analysts say.
French special forces are very likely already operating in the Adrar des Ifoghas, performing reconnaissance and perhaps preparing rescue operations for French hostages believed to be held in the area, said Gen. Jean-Claude Allard, a senior researcher at the Institute for International and Strategic Relations in Paris. But African forces are likely to be assigned the brunt of the combat operations, going "from well to well, from village to village," General Allard said.
The few Westerners who have traveled in this inaccessible region bordering Algeria say it differs from Afghanistan in that the mountains are relatively modest in size. But its harsh conditions make it a vast natural fortress, with innumerable hide-outs.
"The terrain is vast and complicated," said Col. Michel Goya of the French Military Academy's Strategic Research Institute. "It will require troops to seal off the zone, and then troops for raids. This will take time."
The number of militants who remain is in dispute, with estimates varying from a few hundred fighters to a few thousand. They are becoming more dispersed and are hiding themselves ever more effectively, Western military officials say.
The French military has been flying fewer sorties over the region in recent days, "from which I deduce a lack of targets," said a Western military attaché in Bamako, Mali's capital, who was not authorized to speak on the record. "They are just not finding the same targets. Clearly they are hiding better and dispersing more widely."
A ranking Malian officer stationed in the northern town of Gao said: "We don't know how many there are. They have learned to hide where the French can't find them."
The militants are versed in survival tactics in the hills, supplying themselves from the nomads who pass through and getting water from the numerous wells and ponds, said Pierre Boilley, an expert on the region from the Sorbonne. Still, the sources of water are an opportunity for the French and Chadian forces, as they can be monitored without too much difficulty, experts said.
"It's a sort of observation tower on the whole of the Sahara," General Allard said. The fighters have had years to build installations, modify caves, and stock food, weapons and fuel, he said, and the precise locations of their refuges remain a mystery.
Even if the bulk of the militants have retreated into the mountains, pockets remain around the liberated towns of Timbuktu and Gao, said a French military spokesman, Col. Thierry Burkhard. Last week, French forces patrolling the area around Gao engaged in firefights with militants, some of whom fired rockets, officials said.
"We're encountering residual jihadist groups that are fighting," said Jean-Yves Le Drian, France's defense minister.
On Friday, a suicide bomber blew himself up at a military checkpoint in Gao, wounding a soldier, an act that provided further evidence of the continued threat of the militants.
The attack, from an insurgent reported to have ties to the militants who carried out the recent hostage-taking on the internationally managed gas field in eastern Algeria, could signal the opening of a campaign against French and African forces, a senior United States intelligence official said Friday.
"This is what they're going to do -- I.E.D.'s and small attacks," said the official, who spoke on the condition of anonymity, referring to improvised explosive devices, the homemade bombs that were the hallmark of insurgencies in Iraq and Afghanistan.
With France insisting that its presence in the country will be short-lived, more attention has been focused on the liabilities of the tattered Malian Army and troops deployed from neighboring countries.
On Friday, there were clashes between rival factions of the Malian Army in Bamako, with gunfire heard echoing from a barracks of paratroopers hostile to the element that supported a military coup in March.
About 2,000 troops from neighboring countries have arrived, eventually to replace French troops. A Western military official in Bamako said, "There is a difference between them operating in a theater under French control and one where the French have disengaged."
Nor have the militants been completely flushed out of the towns that France has claimed to have liberated.
Amid concerns of violent score-settling, local officials in Gao have broadcast radio messages over the past 10 days asking for the citizens to report suspects to state authorities rather than take matters into their own hands. Community leaders, including local chiefs, youth groups and imams, have held meetings to discourage acts of vengeance.
In one episode on Jan. 26, a crowd encircled an already bloodied militant whose comrades had recently abandoned Gao, recalled Dani Sidi Touré, a resident who was one of those intent on revenge.
"He said, 'Please, for Allah's sake, do not kill me,' " Mr. Touré said. "And then I took my screwdriver and stabbed him in the neck."
Others joined in the attack. "When I tried to pull the screwdriver out, the handle came off but the metal stayed inside him," he continued. "A man with a big knife came over and chopped him on his head. He fell to the ground, and others came with pieces of wood and big stones and started beating him."
American officials monitoring the situation from afar said that the extremists who once controlled much of northern Mali would be difficult to eliminate from the region entirely.
"Realistically, probably the best you can get is containment and disruption so that Al Qaeda is no longer able to control territory," Gen. Carter F. Ham, the head of the Pentagon's Africa Command, said in a speech in Washington last month.
The authorities are investigating numerous other suspected militants as local citizens' patrols circulate in search of the extremists and their allies, which at one time included the Tuaregs.
Adam Nossiter reported from Dakar, and Peter Tinti from Gao, Mali. Eric Schmitt contributed reporting from Washington, and Scott Sayare and Steven Erlanger from Paris.world
This article originally appeared in The New York Times.