Washington has begun sending investigators to Saudi Arabia and the United Arab Emirates over US-made weapons transferred to insurgents, separatist militias and al-Qaeda-linked elements in Yemen, CNN reported.
Since September, the State Department and Pentagon have begun sending teams to the UAE to investigate the findings of the CNN report, which was behind the case, she said.
A similar visit by teams from the two ministries will take place in Saudi Arabia in November.
She explained that the decision to send investigators came after the delay of the joint investigation between the State Department and the Pentagon, due to insufficient responses from the two Gulf allies.
The report quoted Saudi-Emirati coalition spokesman Turki al-Maliki as denying that Riyadh and Abu Dhabi did not cooperate with Washington in this regard. The weapons, which were signed by anti-government groups in Yemen, include MRAPs.
A series of investigations by CNN revealed that US armored vehicles sold to the UAE and Saudi Arabia were transferred to groups including al Qaeda-linked fighters, Iranian-backed insurgents and separatist militias, in violation of the two countries' agreements with Washington.
According to the investigation, the factions have since turned against internationally recognized Yemeni government forces backed by the United States.
A letter from the State Department said that after the visits, the administration of President Donald Trump expects to have a full description of the circumstances regarding the disposal of such equipment and any possible violation of the agreements.
Senate Minority Leader Chuck Schumer said the humanitarian crisis in Yemen must end.
Schumer said in a tweet on Twitter that a bipartisan majority has repeatedly supported the question of President Trump stopping support for the Saudi war in Yemen.
Schumer stressed that the final legislation on defense must include articles to end the war in Yemen.