The move reversed France’s earlier insistence on providing only aerial and logistical support for a military intervention led by African ground troops.

France plunged headfirst into the conflict in its former colony last week, bombarding the insurgents’ desert stronghold in an effort to shatter the Islamist domination of a region many fear could become a launching pad for terrorist attacks on the West and a base for coordination with al-Qaida in Yemen, Somalia and Pakistan.

But despite five days of airstrikes, the rebels have extended their reach, taking over a strategically important military camp in the central Malian town of Diabaly on Monday.

On Tuesday, France announced it was tripling the number of soldiers in Mali from 800 to 2,500. The offensive was to have been led by thousands of African troops pledged by Mali’s neighbors, but they have yet to arrive, making it increasingly apparent that France will be leading the attack and not playing a supporting role.

French President Francois Hollande told RFI radio early Tuesday that he believed France could succeed in ousting the extremists in a week. But by afternoon he had outlined a far longer-term commitment.

“We have one objective: To make sure that when we leave, when we end this intervention, there is security in Mali, legitimate leaders, an electoral process and the terrorists no longer threaten its territory,” he said during a stop in the United Arab Emirates.

“We are confident about the speed with which we will be able to stop the aggressors, the enemy, these terrorists,” he added.

Supplies for the French forces arrived in a steady stream Tuesday, part of the enormous logistics operation needed to support thousands of troops in the baking Sahara sun, a terrain the Islamists have operated in for nearly a decade.

Transport planes bringing military hardware landed in quick succession on the short airstrip: A giant Antonov, two C-17 Boeings and a C-160 disgorged equipment in preparation for a land offensive to try to seize back the northern territory held since March by a trio of rebel groups affiliated with al-Qaida.

Burly French troops in fatigues carried boxes of munitions as armored personnel carriers lined up at the airport’s gasoline pump. Roughly 40 armored vehicles were driven in overnight by French soldiers stationed in Ivory Coast. They include the ERC-90, a six-wheeled vehicle mounted with a 90mm cannon. Dozens of French Marines camped out inside an airport hangar, sleeping on pads laid on the cement floor.

A convoy of French armored cars was spotted late Tuesday heading toward Diabaly, the strategic town seized by the Islamists a day earlier, said a resident of the nearby town of Segou, who declined to be named out of fears for her safety.

The Islamists appeared to be mostly equipped with Russian-made machine guns and other small arms, said a French army adjutant who gave only his first name, Nicolas, in keeping with military regulations. But, he added, the French force would not underestimate the insurgents. On the first day of the operation, a French helicopter gunship was downed by rebel fire.

A French military spokesman said the Islamists had managed to seize more territory despite the air assault because the fighters were embedding themselves with the population, making it difficult to bomb without causing civilian casualties. He spoke on condition of anonymity in keeping with military protocol.

The French Mirage and Rafale fighter jets equipped with 550-pound (250-kilogram) laser- and GPS-guided bombs were useful for taking out convoys of rebel cars in the desert or militant training camps, complexes and warehouses away from urban centers, the spokesman said. But they could not pinpoint rebels embedded with the local population.

U.S. Defense Secretary Leon Panetta said Tuesday that the Obama administration had ruled out putting any American troops on the ground in Mali, but was providing intelligence-gathering assistance to the French. Officials did not rule out having American aircraft land in the West African nation as part of future efforts to lend airlift and logistical support.

Over the weekend, the rebels made their way to the rice-growing region, just north of the central Malian city of Segou, then seized Diabaly, a town of 35,000 that is home to an important military camp, and Niono, the last town before Segou.

France ordered the evacuation of the roughly 60 French citizens living in the Segou region, then pounded the area around Diabaly with bombs all night Monday and again on Tuesday, said Ibrahim Toure, a resident cowering inside a mud-walled home.

“They bombed Diabaly. They bombed the town all night long. I am hiding inside a house,” said Toure. “Everyone is afraid to go out.”

The Islamists taunted the French, saying they had vastly exaggerated their gains.

“I would advise France not to sing their victory song too quickly. They managed to leave Afghanistan. They will never leave Mali,” said Oumar Ould Hamaha, a commander of the Movement for Oneness and Jihad in West Africa, an extremist groups whose fighters are believed to be in Diabaly.

“The French resemble a fly that was attracted to a pot of honey. Now their feet are sticky. They can’t fly away anymore. France has opened the doors of hell,” he said.

“They are bombing us from an altitude of 13,000 meters. It’s to our advantage that they send in French troops on foot. We are waiting for them. And what they should know is that every French soldier that comes into our territory should make sure to prepare his will beforehand, because he will not leave alive.”