The US military has begun flying drone aircraft from a base in Ethiopia, as part of its fight against Islamist militants in neighbouring Somalia.
US officials have confirmed to the BBC that the base, in the southern city of Arba Minch, is now operational.
But they stressed that the remotely-piloted drones were being used only for surveillance, and not for air strikes.
It is part of a growing counter-terrorism presence in the region as the US pursues groups with al-Qaeda links.
The US military has reportedly spent millions of dollars upgrading the remote, civilian airport - from which Reaper drones are now being flown.
The remotely-piloted aircraft can be equipped with missiles and satellite guided bombs.
But officials have told the BBC the drones are flying unarmed because their use is considered sensitive by Ethiopia's government.
Their role is surveillance of the al-Shabab militant group - based in Somalia, and already the focus of drone missions flown from other bases in the region.