The United States last week sanctioned seven executives from an Iranian drone manufacturer and a company overseeing Iran's ballistic missile programmes that have been supplying materiel to Russia for its war on Ukraine.
The US Treasury on January 6 blacklisted six executives and board members of Qods Aviation Industries (QAI), a defence manufacturer responsible for the design and production of unmanned aerial vehicles (UAVs), commonly known as drones.
QAI also operates under the alias Light Airplanes Design and Manufacturing Industries.
The Treasury also blacklisted the director of Aerospace Industries Organisation (AIO), which is responsible for overseeing Iran's ballistic missile programmes.
The United States sanctioned AIO on June 28, 2005.
"Iran has transferred these UAVs for use in Russia's unprovoked war of aggression in Ukraine," the Treasury said in a statement.
Treasury Secretary Janet Yellen said the United States would act swiftly against individuals and entities supporting Iran's UAV and ballistic missile programmes "and will stand resolutely in support of the people of Ukraine".
"We will continue to use every tool at our disposal to deny [Russian President Vladimir Putin] the weapons that he is using to wage his barbaric and unprovoked war on Ukraine," she said.
"The Kremlin's reliance on suppliers of last resort like Iran shows their desperation in the face of brave Ukrainian resistance and the success of our global coalition in disrupting Russian military supply chains and denying them the inputs they need to replace weapons lost on the battlefield," Yellen added.
In a Friday statement, US Secretary of State Antony Blinken said the Iranian regime's military support to Russia has fueled the conflict in Ukraine and resulted in violations of United Nations (UN) Security Council Resolution 2231.
This is through its provision of military UAVs without advance, case-by-case approval of the UN Security Council, Blinken said.
"Iran has now become Russia's top military backer," he said.
"Iran must cease its support for Russia's unprovoked war of aggression in Ukraine, and we will continue to use every tool at our disposal to disrupt and delay these transfers and impose costs on actors engaged in this activity."
The United States in October warned it would take action against companies and nations working with Iran's drone programme after Russia used the imports for deadly strikes in Kyiv.
The latest designation follows the December 9, November 15 and September 8, designations of individuals and entities involved in the production and transfer of Iranian Shahed- and Mohajer-series UAVs.
Russia has been using these drones to attack Ukraine's critical infrastructure.
Among the blacklisted executives is QAI's chairman of the board of directors, Seyed Hojatollah Ghoreishi.
As the head of the Supply, Research and Industry Affairs section of Iran's Ministry of Defence and Armed Forces Logistics and Deputy Minister of Defence, he has led Iran's military research and development efforts.
Ghoreishi was responsible for negotiating Iran's agreement with Russia for the supply of Iranian drones for Russia's war in Ukraine, the Treasury said.
As QAI managing director, blacklisted executive Ghassem Damavandian "has likely facilitated QAI's supply of UAVs to Iranian military services in addition to training Russian personnel on the use of QAI-manufactured UAVs", it said.
Hamidreza Sharifi-Tehrani served as a primary member of the QAI board, the Treasury added, travelling "for international conferences related to UAVs".
He "has undoubtedly been involved in the supply of UAVs and related equipment to Iranian military services", it said.
Also on the QAI board are Reza Khaki, Majid Reza Niyazi-Angili and Vali Arlanizadeh; while AIO director Nader Khoon Siavash oversaw AIO's ballistic missile production and testing and deals with international suppliers.
"Iran's Central Bank has siphoned millions in discounted foreign currency -- ostensibly earmarked for importers of essential goods -- to AIO per year, underscoring the regime's prioritisation of its missile programmes at the expense of its own citizens," the US Treasury said.