The United States on Tuesday imposed financial sanctions on two additional Iranian companies suspected of helping to proliferate weapons of mass destruction through their involvement in the country's nuclear program. The action by the Treasury Department's Office of Foreign Assets Control targets Sanam Industrial Group and Ya Mahdi Industries Group, which are said to be owned, controlled by, or agents of the Aerospace Industries Organization of Iran, a subsidiary of the Iranian Ministry of Defense and Armed Forces Logistics. The Treasury Department ordered US banks to freeze any bank accounts or other financial assets found in the United States that belong to Sanam and Ya Mahdi. The US government also is prohibiting Americans from doing business with them. Sanam has purchased millions of dollars of equipment on the AIO's behalf from companies linked to missile proliferation, according to Treasury. It said that Ya Mahdi has been involved in international purchases of missile-related technology and goods on the AIO's behalf. The action brings to 13 the number of companies sanctioned by the administration for suspected ties to Iranian proliferation; they include four Chinese and one American firm. "As long as Iran's nuclear ambitions continue to threaten the international community, the United States will use its authorities to target Iran's efforts to sell and acquire items used to develop weapons of mass destruction and the missiles capable of carrying them," Stuart Levey, Treasury undersecretary for terrorism and financial intelligence, said in a statement.