The United States Treasury has imposed sanctions against companies connected with the Iranian Islamic Revolutionary Guards. The action extends earlier sanctions against the Guards and its construction company headquarters. It aims to freeze the foreign assets of four companies connected to Khatam al-Anbiya Construction and its chief officer. <br/><br/>The company's profits help fund Iran's nuclear and missile programmes, the US Treasury said. Washington says, the company is the construction arm of the Iranian Revolutionary Guards, which is a wing of the Iranian army, founded after the 1977 revolution. <br/>Meanwhile, Iran has turned down US proposal that Iran shut down its Tehran research reactor and purchase medical isotopes instead.<br/><br/>Talking to IRNA news agency, Iranian foreign Ministry spokesman Ramin Mihmanparast said in Tehran yesterday that the US proposal is illogical since a large group of patients are in need of such medicines.<br/><br/>He urged the US and its allies to refrain from exerting political and economic pressures on Iran as Iran’s nuclear program is peaceful.<br/><br/>In a related development Iran Atomic Energy Organization chief Ali Akbar Salehi has said that a nuclear fuel exchange with the West is still possible. But he reiterated Iran's demand for a simultaneous fuel swap.<br/><br/>The United States is targeting affiliates of Iran's Revolutionary Guard Corps with new sanctions designed to curtail the activities of individuals and companies involved in Iran's nuclear and missile program. The U.S. Treasury Department has announced that it is freezing the assets of Revolutionary Guard General Rostam Qasemi and four subsidiaries of a construction company he oversees for the military.<br/><br/>