WASHINGTON — Plans to base unarmed American surveillance drones in the African nation of Niger highlight the Obama administration’s growing concern about extremist influences in the volatile region. They also raise tough questions about how to contain al-Qaida and other militant groups without committing U.S. ground forces in yet another war.

In the short run, a drone base would enable the U.S. to give France more intelligence on the militants that French troops are fighting in neighboring Mali. Over time, it could extend the reach not only of American intelligence gathering but also U.S. special operations missions to strengthen Niger’s own security forces.

The U.S. and Niger in recent days signed a “status of forces agreement” spelling out legal protections and obligations of American forces that might operate in Niger in the future.

Pentagon spokesman George Little acknowledged the agreement, but declined Tuesday to discuss U.S. plans for a military presence in Niger.

“They expressed a willingness to engage more closely with us, and we are happy to engage with them,” Little said, adding that the legal agreement was months in the making and saying it was unrelated to the recent fighting in Mali.

The U.S. has found some of its efforts to fight extremists hobbled by some African governments, whose own security forces are ill-equipped to launch an American-style hunt for the militants yet are reluctant to accept U.S. help because of fears the Americans will overstay their welcome and trample their sovereignty.

At France’s request, the U.S. has flown 17 Air Force transport flights to move French troops and their equipment to Mali in recent days, Little said. U.S. aircraft also are conducting aerial refueling of French fighter jets based in Mali, he said, and those operations will continue.

Other U.S. officials said the Pentagon is planning a new drone base in northwestern Africa — most likely in Niger — but the plans are not yet complete. It would provide more extended U.S. aerial surveillance of militants in the region without risking the loss of air crews. The main U.S. drone base in Africa is in Djibouti in East Africa.

Niger has accepted the idea of hosting unarmed U.S. drones as well as conventional and special operations troops to advise and assist Niger’s military on border security, but it has not endorsed armed U.S. Predator strikes or the launching of U.S. special operations raids from their territory, according to a senior U.S. military official briefed on the matter.