White House National Security Council spokesman John Kirby said Russia is looking to Iran once again to resupply the Russian military with drones and surface-to-surface missiles.

"Russia is offering Iran an unprecedented level of military and technical support that is transforming their relationship into a fully fledged defence partnership," Kirby said.

"I think it's important for us to be clear this partnership poses a threat not just to Ukraine, but to Iran's neighbours in the region."

Concerns about new weapon sales to Russia come after Iran sold hundreds of attack drones to Russian over the summer.

The Biden administration recently unveiled sanctions against Iranian firms and entities involved in the transfer of Iranian drones to Russia for use in Putin’s ongoing invasion of Ukraine.

In October, the White House accused Tehran of sending Iranian troops to Crimea to support Russian drone attacks on Ukraine’s power stations and other key infrastructure,

The White House and British government said the relatively small number of Iranian personnel deployed to Crimea, a part of Ukraine unilaterally annexed by Russia in contravention of international law in 2014, were there to assist Russian troops in launching Iranian-made drones against Ukraine.

"Support is flowing both ways," said Kirby.

"Russia is seeking to collaborate with Iran on areas like weapons development and trade. As part of this collaboration, we are concerned that Russia intends to provide Iran with advanced military components."

BBC