Iran has said it has shown Russia U.S. drones it shot down over the Gulf, Revolutionary Guards aerospace commander Brigadier General Amir Ali Hadjizadeh was quoted as saying on Tuesday.

“Russian experts requested to see these drones and they looked at both the downed drones and the models made by the Guards through reverse engineering,” the official IRNA news agency quoted Hadjizadeh as saying.

Hajizadeh did not elaborate on the number or type of unmanned U.S. aircraft it had shot down, or when or where it had done so.

Iran announced on January 2 that its forces had downed two U.S. drones after they “violated” Iranian-controlled territory. It later said it would put the aircraft on public display.

“The planes that were shot down are among the most modern U.S. navy drones and have a long-range capability,” the Fars news agency quoted the commander of the Guards’ naval forces, Ali Fadavi, as saying at the time.

The US navy’s Fifth Fleet is based in Bahrain, just across the Gulf from Iran. Washington never confirmed Tehran had shot down any of its drones.

The U.S. military and Central Intelligence Agency routinely use drones to monitor military activity in the region. 

They have also used them to launch missile strikes in Yemen as well as in Afghanistan and Pakistan’s lawless tribal belt.

On several occasions, the Iranian military has shown off drones which it says it manufactured itself using the latest technology. Washington has expressed concern about Tehran’s possession of the aircraft.