Russia accused the US and its western allies on Wednesday of "openly" breaching Article 100 of the UN Charter, by supporting Ukraine's call for Secretary General Antonio Guterres to send a team to investigate drones used to attack Ukraine.
"They talked about the need to protect the UN Charter today and they are openly violating it; and they are prompting the Secretary General to do so as well," said Vassily Nebenzia, Russia's ambassador to the UN.
Mr Nebenzia said the US had been breaching the charter for the past four years by withdrawing in 2018 from the Iran nuclear agreement, officially called the Joint Comprehensive Plan of Action).
Former president Donald Trump withdrew the US from the JCPOA, signed by Tehran and world powers in 2015, calling it the “worst deal in history”.
The US on Friday sent a letter saying Iranian Mohajer and Shahed-series drones were transferred to Russia in late August.
It requested the UN Secretariat team responsible for monitoring the resolution’s implementation to “conduct a technical and impartial investigation that assesses the type of UAVs involved in these transfers".
The US Deputy ambassador to the UN, Robert Wood, countered by calling Russia's allegations "simply dumbfounding".
Mr Wood said that "Article 100 provides that the Secretary General and the staff shall not seek or receive any instructions from any government".
He said the requests of the US and other council members were not “instructions" and he regretted that Russia had once again abused its position as a council member.
"If Iran had wanted to do this legally, if Russia had wanted to receive these drones legally, they would have had to come to the Security Council for approval," a US administration official said earlier.
Given that no prior approval was sought or granted by the council, these transfers represent breaches of Resolution 2231, UK deputy envoy to the UN James Kariuki said.
"We have therefore expressed support for an impartial, expert investigation by the UN Secretariat, in line with its mandate under Resolution 2231, so the facts can be clearly established," he said.
Resolution 2231 was adopted by the UN's most powerful body in 2015 to endorse an agreement between Iran and the US, Russia, China, Britain, France and Germany aimed at curbing Tehran’s nuclear activities.
