WASHINGTON (AP) — President Barack Obama said Friday that about 100 American troops have been deployed to the African nation of Niger. Two US defense officials said the troops would be setting up a base for unarmed drones to conduct surveillance.

Obama announced the deployment in a letter to Congress, saying that the forces “will provide support for intelligence collection and will also facilitate intelligence sharing with French forces conducting operations in Mali, and with other partners in the region.”

The move marks a deepening of US efforts to stem the spread of al-Qaeda and its affiliates in the volatile region. It also underscores Obama’s desire to fight extremism without involving large numbers of US ground forces.

The drone base will allow the US to give France more intelligence on the militants its forces have been fighting in Mali, which neighbors Niger. Over time, it could extend the reach not only of American intelligence-gathering but also US special operations missions to strengthen Niger’s own security forces.

One of the two US defense officials who discussed the development confirmed the American troops would fly drones and other surveillance platforms from Niger military airstrips, tracking militant and refugee movement inside Mali and around the border. The US will share that intelligence with Niger’s military, the official said.

Both officials spoke on the condition of anonymity because they were not authorized to publicly discuss the project.

The drones at the Niger base will be unarmed and used for surveillance, not airstrikes. Still, the development of a base in Niger raises the possibility that it could eventually be used for launching strikes.

Obama said in his letter to Congress that the US forces have been deployed with the consent of Niger’s government. The forces were also deployed with weapons “for their own force protection and security,” the president said.

Last month, the US and Niger signed a status-of-forces-agreement spelling out legal protections and obligations of American forces that might operate in Niger in the future.

Africa is increasingly a focus of US counterterrorism efforts, even as al-Qaeda remains a threat in Pakistan, Yemen and elsewhere. Last month’s terrorist attack on a natural gas complex in Algeria, in which at least 37 hostages and 29 militants were killed, illustrated the threat posed by extremists who have asserted power propelled by long-simmering ethnic tensions in Mali and the revolution in Libya.

A number of al-Qaeda-linked Islamic extremist groups operate in Mali and elsewhere in the Sahara, including a group known as al-Qaeda in the Islamic Maghreb, or AQIM, which originated in Algeria and is active in northern Mali. Earlier this month, French forces intervened to stop the extremists’ move toward Mali’s capital, and Washington has grown more involved by providing a variety of military support to French troops.

France has said it will eventually pull out of its Mali operation so that African forces can help stabilize the West African country.

Copyright 2013 The Associated Press.