Cape Town — American forces in Africa will soon escalate their war against militants in the Sahel by using armed drones to attack them, reports an American news website on global affairs.

The attacks will be launched in the coming months from new facilities which the United States Air Force is building at Agadez in central Niger, says the Washington-based Foreign Policy news service.

The U.S. military has killed al Shabaab militants in drone strikes in Somalia for some time. But Foreign Policy reports that in the Sahel, the drones have until recently been based in the Nigerien capital, Niamey, and used only to collect intelligence.

The service says the government of Niger asked the U.S. to deploy armed drones after an ambush last November in which militants claiming to be from "Islamic State in the Greater Sahara" killed five Nigerien and four American troops.

The deaths of American Special Forces soldiers in a little-publicised war in which they were not assigned to combat roles led to an extensive inquiry in Washington.

The inquiry found that a lack of training, proper equipment and preparation for the mission had contributed to the deaths. The 46 U.S. and Nigerien troops involved had been outnumbered three to one in show of force never previously mounted by the militant group.