The U.S.military launched six drone strikes against Islamic State positions in Libya on Friday, months after militants were driven from safe havens there.

Officials announced the operation Sunday, saying 17 militants were killed and three vehicles were destroyed when unmanned aircraft targeted a desert camp about 150 miles southeast of Sirte, a coastal city where ISIS fighters were defeated by U.S.-backed Libyan forces last September.

Sirte served as an important logistics hub for ISIS leaders, and was considered a potential fallback if the group were to lose its de facto capital in Syria.

Friday’s operation was the first reported U.S. strike inside Libya since late January.

In that attack, an estimated 80 ISIS militants were killed 30 miles from the Mediterranean coast.