The Pentagon has secretly expanded its global network of drone bases­ to North Africa, deploying unmanned aircraft and U.S. military personnel to a facility in Tunisia to conduct spy missions in neighboring Libya.

The Air Force Reaper drones began flying out of the Tunisian base in late June and have played a key role in an extended U.S. air offensive against an Islamic State stronghold in neighboring Libya.

The Obama administration pressed for access to the Tunisian base as part of a security strategy for the broader Middle East that calls for placing drones and small Special Operations teams at a number of facilities within striking distance of militants who could pose a threat to the West.

U.S. officials, speaking on the condition of anonymity to discuss an operation that has not been acknowledged, said the drones being flown out of Tunisia were unarmed and were principally being used to collect intelligence on Islamic State targets in Sirte, Libya, where the United States has conducted more than 300 airstrikes since August.