The United States will continue to take "practical, aggressive" steps to make it harder for Iran to sell drones and missiles to Russia, State Department deputy spokesperson Vedant Patel said on Tuesday, adding that Washington had a number of tools to hold both Moscow and Tehran accountable.
Patel, speaking at a daily press briefing, said such measures could include sanctions and export controls.
"We will continue to take practical, aggressive steps to make these weapons sales harder, including sanctions, export control actions against any entities involved," Patel said.
"Russia deepening an alliance with Iran is something the entire world - especially those in the region - should view as a profound threat."
Ukraine has accused Russia of using Iranian-made Shahed-136 drones in attacks in recent weeks. Iran denies supplying them and on Tuesday the Kremlin also denied using them.
Reuters reported on Tuesday that Iran has promised Russia it would supply them with surface to surface missiles, in addition to more drones.
The U.S. State Department assessed that Iranian drones were used on Monday in a morning rush hour attack on the Ukrainian capital Kyiv, a U.S. official said. White House spokesperson Karinne Jean-Pierre also accused Tehran of lying when it said Iranian drones were not being used by Russia in Ukraine.
The United States in September imposed sanctions on an Iranian company it accused of coordinating military flights to transport Iranian drones to Russia and three other companies it said were involved in the production of Iranian drones.
(Reporting by Daphne Psaledakis, Humeyra Pamuk and Doina Chiacu, Editing by Rosalba O'Brien)