French officials said they are concerned with concentrations of armed militants from al-Qaida in the Islamic Maghreb, also known as AQIM, at two sites, the BBC reported Wednesday.
One is the towns is Diabaly, some 250 miles northeast of Mali's capital of Bamako, and the other is the village of Konna, the first place to fall to Islamists, they said.
Until now, the main French effort against the rebels has been aerial bombardment of their positions using fighter jets and helicopters.
When France started attacks against AQIM and its allies in northern Mali plans were for only several hundred French soldiers to take part.
Wednesday the total due in Mali rose to 2,500.
French President Francois Holland vowed the campaign will end only when "Mali is safe, has legitimate authorities, an electoral process and there are no more terrorists threatening its territory."
Hollande's decision to intervene has drawn widespread support in France with a public-opinion survey indicating 75 percent of the French people back the military campaign.
The international community is concerned militants will create a terrorist haven in the country that analysts warn has the potential to become the next Afghanistan.
U.S. State Department spokeswoman Victoria Nuland said the United States has fielded "a number of requests for support from the French."
U.S. policy prohibits direct military aid to Mali because the fledgling government resulted from a coup, CNN reported Wednesday.
No support can go to the Malian military directly until democracy has been restored, Nuland said.
So far, the United States has shared only intelligence from satellites and intercepted signals with the French, defense officials told CNN.
U.S. Defense Secretary Leon Panetta, traveling in Spain, said the Pentagon remained in talks with France on what sort of aid was required.
"Our goal is to do what we can," Panetta said. "The fundamental objective is to ensure that AQIM -- al-Qaida -- never establishes a base of operations in Mali or anywhere else."
Rogers said Washington could offer a wide range of support without committing ground troops. He declined to say what he saw that support as being.