Story highlights United States agrees to conduct aerial refueling missions, to transport troops

Malian and French forces recapture the city of Gao, a stronghold of the Islamic militants

The Malian offensive is backed by French forces

The United States is intensifying its involvement in Mali, where local and French forces are battling Islamic militants.

It will support the French military by conducting aerial refueling missions, according to the Pentagon, which released a short statement Saturday following a call between Defense Secretary Leon Panetta and French Defense Minister Jean-Yves Le Drian.

"The leaders also discussed plans for the United States to transport troops from African nations, including Chad and Togo, to support the international effort in Mali. Secretary Panetta and Minister Le Drian resolved to remain in close contact as aggressive operations against terrorist networks in Mali are ongoing," it read.

U.S. policy prohibits direct military aid to Mali because the fledgling government is the result of a coup. No support can go to the Malian military directly until leaders are chosen through an election.

But the United States is supporting the effort with intelligence and airlift support.

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So far, the U.S. Air Force has flown at least seven C-17 cargo missions into Mali, carrying 200 passengers, mainly French troops, and 168 tons of equipment, according to Maj. Robert Firman, a Pentagon spokesman.

The uptick in U.S. involvement comes as Malian forces loosened the grip that Islamist militants' hold in the country's north with the retaking of the city of Gao.

With the support of French forces, the Malians entered and took control of Gao, which for months had been a militant stronghold, the French defense ministry said.

The advance was made in stages, with forces taking Gao's airport and the main bridge leading to town before entering the rest of the city.

"Jihadist terrorists, who have fought Malian and French armies, have seen their mobile and logistical capabilities reduced," the ministry said in a news release.

The quickening advance of the government forces has brought them to the heart of the territory held by the militants.

The Islamic extremists carved out a large haven in northern Mali last year, taking advantage of a chaotic situation after a military coup by the separatist party MNLA. The militants banned music, smoking, drinking and watching sports on television. They also destroyed historic tombs and shrines.

The takeover stoked fear among global security experts that Mali could become a new hub for terrorism.

Refugees tell harrowing stories of life under the Islamist militants.

But the French-based International Federation for Human Rights said it is "very alarmed" by reports that Malian soldiers are themselves carrying out extrajudicial killings and abuses as they counterstrike.

The United Nations' refugee agency, UNHCR, has called for an increase in international aid for the hundreds of thousands of people who have been displaced by the fighting in the country.

More than 150,000 refugees have fled Mali into neighboring countries, and another 230,000 are displaced inside Mali, the agency said.

The military's advance into Gao may shed more light on the conditions that residents there have faced. According to the U.N. agency, one former resident told of a hospital stripped of medicine by the armed militants and filling with bodies.

As the Malian troops advance, some other countries in the region are joining the French force aiding them. Between 700 and 800 African troops from Benin, Nigeria, Togo and Burkina Faso have arrived, U.S. State Department spokeswoman Victoria Nuland said Friday, and a number of Senegalese troops and up to 2,000 from Chad are on the way.

France has 2,150 soldiers on Malian soil, with 1,000 more troops supporting the operation from elsewhere.

French involvement in the conflict began on January 11, the day after militants said they had seized the city of Konna, east of Diabaly in central Mali, and were poised to advance south toward Bamako, the capital.

Until 1960, Mali had been under French control.