Ukraine war: US says Iran now Russia's 'top military backer'

Russia and Iran's relationship has warmed to a fully fledged defence partnership, the US has said.

Russia is giving an unprecedented level of military support, says US national security council spokesman John Kirby.

The US has seen reports that the two countries are considering joint production of lethal drones, he adds.

It comes after Ukraine accused Iran of supplying Russia with "kamikaze" drones used in deadly attacks on 17 October, which Tehran initially denied.

The Middle Eastern country later admitted sending Moscow a limited number of drones, "many months" before...