Russian officials have reacted sharply to the sanctions imposed by the United States against two major weapons firms, calling the action "unlawful." The sanctions were announced in Washington on Friday.
Russia's Foreign Ministry reacted quickly to the U.S. sanctions, calling the move "unacceptable."
U.S. officials decided to impose sanctions against Russia's major airplane manufacturer Sukhoi, as well as the state arms export monopoly Rosoboronexport.
Both firms allegedly provided Iran with equipment and expertise that Tehran could use to develop missile systems or weapons of mass destruction.
Sanctions were also imposed against five other companies in Cuba, North Korea and India.
The measure prohibits U.S. government agencies from purchasing goods or offering any assistance to the various companies. It also bars the sale of sensitive military equipment or services to the firms or their subsidiaries.
U.S. government agencies currently have no contracts with any of the firms. But the measure could affect a project between Sukhoi and the U.S.-based aeronautics firm Boeing to develop civilian aircraft.
Sukhoi officials deny having sold any military equipment to Iran in the past six or seven years.
Sergei Chemezov, head of Russia's arms export firm, also denounced the sanctions.
Chemezov says all Russian arms sold to different countries are purely defensive in character. He says the U.S. move, which he characterized as "illegal," will have a negative impact on the American-Russian partnership.
The United States has often expressed concern about Russian arms sales, including a lucrative deal to provide Iran with a sophisticated anti-missile system.
Last week, Moscow also sold dozens of Sukhoi fighters and other weapons to Venezuela during a visit by President Hugo Chavez, who Washington accuses of destabilizing Latin America.
The U.S. sanctions come amid sensitive diplomatic discussions with Russia on issues such as the Middle East crisis and Iran's controversial nuclear program.