Russia is experiencing “numerous failures” and technical glitches with drones it purchased from Iran for use in Ukraine.

Biden administration officials said that the technical problems began after Russia took delivery of the first shipment of Mohajer-6 and Shahed Iranian-made drones over a several day period this month, the start of a Russian move to purchase hundreds of Iranian UAVs, the Associated Press reported.

Russia’s technical issues with the drones was first reported in the Washington Post, with sources saying that Russian drone operators were being given training in Iran on the UAV systems. The drones are capable of air-to-surface attacks and battlefield cyber warfare.

The White House released satellite images in July that showed Russian officials visiting an Iranian airfield on two separate occasions to inspect domestically produced drones.

In addition, White House national security adviser Jake Sullivan said that the US government had “information that the Iranian government is preparing to provide Russia with several hundred UAVs.”