The American-made weapons, supplied to Washington's allies waging a war on Yemen, end up in the hands of US-backed militants fighting against each other in the impoverished state, CNN reports.
A new CNN investigation released on Saturday found that that American military hardware has been distributed to militant groups in Yemen, including the UAE-backed southern separatists, al-Qaeda-linked militants and hardline Salafi militias.
The Emirati-supported elements, it added, are using American arms to fight the Saudi-led militants loyal to ex-Yemeni president Abd Rabbuh Mansur Hadi, who are also armed with US weapons.
In another probe back in February, CNN had found that the US-made equipment sold to Saudi Arabia and the UAE were being passed to militants in Yemen in violation of arms sales law. The findings led the Pentagon to launch an investigation into the unauthorized transfer of US weapons in Yemen.
US Senator Elizabeth Warren from Massachusetts, who is running for the Democratic presidential nomination, announced her intention to pursue the findings with the administration of President Donald Trump.
"One report of US military equipment ending up in the hands of our enemies is troubling. Two reports is deeply disturbing," she said. "The Defense and State Departments have not yet provided answers to questions I asked back in February and I intend to follow up."
Analyzing social media video of militant infighting in southern Yemen, CNN found multiple instances of American Mine-Resistant Ambush Protected (MRAP) vehicles being used by UAE-backed groups, such as Alwiyat al-Amalqa or the Giants Brigade.
CNN also filmed a BAE Caiman being used by Emirati-backed separatist militants in Shabwah Province in August. The armored vehicle can be traced back to a $2.5 billion arms sale contract between Washington and Abu Dhabi in 2014.
Responding to the latest evidence, a UAE official said, "There were no instances when US-made equipment was used without direct UAE oversight. Except for four vehicles that were captured by the enemy."
Recently, Senator Chris Murphy from Connecticut authored an amendment to the annual US defense spending bill that would cut off support for the Saudi-led coalition until the Secretary of Defense could certify that both the Saudis and Emiratis have stopped transferring US weapons to third parties in Yemen.
"For years, US-made weapons have been fueling the conflict in Yemen and it's no surprise they are now ending up in the hands of private militias," he said in comments about CNN's latest findings.
"This exposes sensitive military technology and endangers our soldiers. It's also a violation of US end-use agreements that govern our arm sales," he added.
As many as 100 Christian faith leaders from 50 states this week wrote an open letter calling for Congress to cut off arms sales and military support to Saudi Arabia and the UAE.
The United Nations said last month that countries that supply weapons to parties involved in Yemen's conflict may be complicit in war crimes.
A UN-commissioned panel of experts has also recommended that the US, UK and France "refrain from providing arms to parties to the conflict".
Saudi Arabia is the United States’ largest arms client, with over $129 billion in approved purchases.
Saudi Arabia and a coalition of its vassal states launched the war on Yemen in March 2015 in an attempt to reinstall the Riyadh-backed former regime of Hadi and eliminate the Houthi Ansarullah movement.
The Western-backed military aggression, coupled with a naval blockade, has destroyed the country’s infrastructure, and led to a massive humanitarian crisis.