US official: Iran may be ‘contributing’ to Russia’s war crimes by supplying drones.

U.S. National Security Adviser Jake Sullivan said on Jan. 9 that Iran may be “contributing to widespread war crimes” by selling lethal drones to Russia for use in its ongoing invasion of Ukraine.

“Iran had chosen to go down a road where their weapons are being used to kill civilians in Ukraine and to try to plunge cities into cold and darkness, which from our point of view, puts Iran in a place where it could potentially be contributing to widespread war crimes,” Sullivan said.

On Jan. 6, the U.S. announced new sanctions against Iran’s aviation and defense sectors for supplying the drones Russia uses to bomb Ukraine’s civilian infrastructure.

U.S. President Joe Biden's administration has scrambled to try to block Tehran from supplying the drones, many of which use Western-made parts.

However, it’s difficult to control these parts, many of which are widely available and have civilian applications.

Ukraine has shot down more than 500 drones launched by Russia since September, according to Ukraine's Air Force.