In a letter dated October 19, Warren called for imposing sentences on officials who might have been associated with or aware of the assassinations.
In the letter which was released on Monday, the democrat senator, referred to US laws and said hiring American veterans to conduct assassinations in Yemen violates law and amounts to crime.
In another letter to US Secretary of State Mike Pompeo, Warren raised questions in this regard.
Warren asked Pompeo to launch an investigation into the issue and provide a report on the role of US Department of State in assassinating Yemeni leaders.
Earlier, Buzzfeed News had reported 'the United Arab Emirates hired U.S. mercenaries to carry out assassinations of Yemeni leaders' in Aden in southern Yemen.
Buzzfeed also claimed Muhammad Dahlan, a former member of Fatah Movement and current advisor to Mohammed bin Zayed, the crown prince of Abu Dhabi, has played a key role in concluding relevant deals with the US.
Since March 2015, a coalition of several Arab countries led by Saudi Arabia and the go-ahead and assistance from the United States launched assaults on Yemen, the Arab world's poorest country under the pretext of bringing the ousted Yemeni President Mansour Hadi back to office.
The Saudi incursion into Yemen has thus far claimed the lives of 16,000 innocent Yemenis and has razed the country to the ground.