American military hardware is being used to undermine official U.S. policy in Libya, TIME has learned, as the United Arab Emirates has deployed warplanes manufactured in the U.S. in Libya in violation of a United Nations arms embargo.

At least six U.S.-made turboprop planes appear in satellite images of an airbase in eastern Libya, deployed in support of the forces of rogue Libyan general Khalifa Haftar, whose army is fighting the U.S. and U.N.-backed government located in Libya’s capital, Tripoli.

The planes offer fresh evidence of a clandestine proxy war in Libya, in which Egypt, the U.A.E., and Russia are siding with Haftar in a military campaign against forces allied with the U.N.-brokered government. Officials in Haftar’s camp accuse Turkey and Qatar of arming Islamist-leaning militias. […]