WASHINGTON (AP) — The U.S. Treasury Department announced Thursday that it is levying sanctions against four Iranian companies that it says were involved in sending drones to Russia last month for use in Moscow’s war against Ukraine.

Tehran-based Safiran Airport Services, Paravar Pars Company, Design and Manufacturing of Aircraft Engines, and Baharestan Kish Company were all hit with the new sanctions.

“Russia is making increasingly desperate choices to continue its unprovoked war against Ukraine, particularly in the face of our unprecedented sanctions and export controls,” said Brian Nelson, under secretary of the Treasury for terrorism and financial intelligence “The United States is committed to strictly enforcing our sanctions against both Russia and Iran and holding accountable Iran and those supporting Russia’s war of aggression against Ukraine.”

Safiran coordinates Russian military flights between Iran and Russia, including those that U.S. intelligence officials say transported Iranian unmanned aerial vehicles, personnel, and related equipment from Iran to Russia, over several days last month.

Paravar Pars Company is closely associated with Iran’s powerful Revolutionary Guard Corps-controlled Imam Hossein University, and has been involved in the research, development, and production of the Iranian Shahed-171 UAV. Design and Manufacturing of Aircraft Engines is an Iranian company involved in the research, development, and production of the Iranian Shahed-171 UAV. Baharestan Kish Company oversees various defense-related projects in Iran, including the manufacturing of UAVs.

The Biden administration said last week that Russia has faced technical problems with Iranian-made drones that were acquired from Tehran in August. The White House says Russian officials picked up Mohajer-6 and Shahed-series unmanned aerial vehicles over several days last month. The Biden administration says U.S. intelligence officials have determined that Russia is looking to acquire hundreds of Iranian UAVs for use in Ukraine.

Earlier this week, the Pentagon confirmed that the U.S. intelligence community has determined that Russia is also in the process of purchasing rockets and artillery shells from North Korea for its ongoing fight in Ukraine.

The U.S. has frequently downgraded and made public intelligence findings over the course of the grinding war in Ukraine to highlight Moscow’s difficulties in prosecuting the war. Ukraine’s smaller military has put up a stiff resistance against the militarily superior Russian forces.

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