U.S. National Security Council Coordinator for Strategic Communications John Kirby said this at a briefing in Washington on Thursday, according to an Ukrinform correspondent.
"There's clearly a growing relationship in the defense realm between these two countries. And as I've also said, it's not only not good for the people of Ukraine, it's really not good for the people of the Middle East. And Iran, which can get its hands on additional military capabilities, some sophisticated capability, only makes their destabilizing activity all the more worrisome," he said.
Kirby recalled that the defense partnership between Iran and Russia had been growing for several months.
"The obvious proof of that are the drones that Iran continues to provide to the Russians. They've also helped Russia create a manufacturing facility on Russian soil so they can build their own Iranian-model drones, which are continuing to attack the people of Ukraine and Ukrainian infrastructure," he said.
Iran, for its part, is also negotiating with Russia about weapons.
"We have reason to believe that they want their hands on some sophisticated Russian military capabilities - attack helicopters, maybe fixed-wing aircraft, cruise and/or ballistic missiles," Kirby said.
Earlier reports said that Kremlin leader Vladimir Putin had invited Iranian President Ebrahim Raisi to visit Russia for a two-day visit on December 7-8. Among the topics they are going to discuss are the expansion of economic relations between the two countries, regional and international problems, as well as the latest events in the Gaza Strip.