Saudi Arabia and its coalition gave al Qaeda, Salafi militias and other factions in Yemen weapons that were produced by the United States, CNN reported Monday.
The weapons have also reportedly been captured by Iranian-backed rebels groups fighting the coalition in Yemen, meaning they may be reverse-engineered for intelligence.
A Department of Defense official confirmed to CNN that the U.S. is investigating the issue, as transferring military equipment to a third party would violate U.S.-Saudi coalition arms agreements.
Local commanders and analysts told CNN during its investigation that the Saudis and the United Arab Emirates use weapons given to the them by the U.S. as currency to buy off factions and militias in the Yemeni conflict.
In the aftermath of the killing of journalist Jamal Khashoggi in the Saudi embassy in Istanbul, the U.S.'s role in the Saudi-led war in Yemen has been under increased scrutiny.
Many lawmakers believe that Saudi Crown Prince Mohammed bin Salman ordered the murder, and do not support the current administration's assistance to the Saudi Arabia in the war against Yemen because of that alleged involvement.
The Senate voted 56-41 in December to pass a resolution that would withdraw U.S. forces in or “affecting” Yemen, except troops fighting al Qaeda and associated forces.
However, the then-Republican controlled House blocked Yemen war powers resolutions from coming to the floor for a vote.
In the new Congress, it is expected that lawmakers will once again push Trump to change the administration's policy toward Saudi Arabia.
Rep. Ro Khanna (D-Calif.) told The Hill on Wednesday that he expects the resolution on the House floor in the next month.
"This will be the first time in the history of this country since 1973 that we will successfully pass a war powers resolution through the Senate and through the House," Khanna said.
Trump is unlikely to sign the war powers measure into law, given that he threatened to veto the Senate bill last year.
The Trump administration did end its mid-air refueling support of Saudi-led coalition aircraft in November.
