Saudi Arabia has given American-made weapons to al Qaeda-linked fighters, militant factions in Yemen, and possibly even Iranian-backed rebels, an investigation by CNN has found. The Saudis and their coalition partners are reportedly using the U.S. arms as a way to buy the loyalties of militias or tribes and influence the political landscape in Yemen. But giving military equipment to third parties is against the terms of Saudi Arabia’s arms deals with Washington, and a U.S. defense official confirmed to CNN that there is an investigation into the situation. CNN’s report comes as Congress, angered by the murder of Jamal Khashoggi last year, is mulling whether to challenge the Trump administration’s support for the Saudi coalition that relies on American weapons to conduct its war. Recipients of American weapons can’t give or sell the equipment to third parties without authorization from the U.S. government—that was never obtained.