The action means that any bank accounts or other financial assets belonging to the company that are found in the United States are frozen. Americans also are forbidden from doing business with the company and its affiliates in Iran and at least nine other countries, including Britain, Belgium, China, Egypt, Italy, Germany, Malta, Singapore and South Korea.
Officials said the step also reinforces a United Nations call for the company's ships to be thoroughly inspected if they are suspected of carrying illicit material. The announcement was accompanied by a list of 123 known IRISL vessels identified by type, tonnage and flag to help maritime authorities spot ships that might bear scrutiny.
In addition, officials said it should send a clear warning, particularly to maritime insurance firms, to be wary of doing business with the line. IRISL is one of Iran's largest, if not the largest, commercial shipping lines, although it is not believed to be a major carrier of Iranian crude oil or other petroleum products, the officials said.
The step marks the latest effort to tighten the financial noose on Iran, which the United States accuses of bankrolling terrorism and seeking a nuclear bomb. The United States has already imposed sanctions on several state-run Iranian banks and businesses along with elements of its defense ministry and Revolutionary Guards Corps.
The United States alleges that the Iranian shipping company facilitated shipments of "military-related cargo" destined for Iran's Ministry of Defense and Armed Forces Logistics. The United States alleges the company falsified documents to conceal its cargo.
"Not only does IRISL facilitate the transport of cargo for U.N. designated proliferators, it also falsifies documents and uses deceptive schemes to shroud its involvement in illicit commerce," Stuart Levey, the Treasury Department's undersecretary for terrorism and financial intelligence said in a statement.
"IRISL's actions are part of a broader pattern of deception and fabrication that Iran uses to advance its nuclear and missile program," he said in a statement released as he was in Europe briefing U.S. allies there on the decision.
The statement offered no direct evidence for the company having transported nuclear related material, but said that in 2007 the firm had been caught shipping a chemical "destined for use in Iran's missile program." No other examples of malfeasance were listed.
The U.N. Security Council has passed three round of sanctions on Iran and a fourth set has been talked about - with the aim of curtailing the country's nuclear and missile program. Iran insists its enrichment program is intended to produce fuel for nuclear reactors that would generate electricity and has vowed to push ahead with it.
Despite those sanctions, Iran has thus far refused to comply with demands to halt suspect activities or accept a package of incentives, including a suspension of new sanctions, to stop enriching uranium that it has been offered by the five permanent members of the Security Council - Britain, China, France, Russia and the United States - and Germany.
U.S. officials made clear on Wednesday that the offer still stands but that unless and until Iran accepts, it will continue to face both unilateral sanctions from the United States and European nations and punitive measures from the United Nations.
"So far, Iran has not responded in a clear, positive way," said Jeffrey Feltman, a senior official in the State Department's Bureau of Near Eastern Affairs. "That leads to looking for ways to incrementally increase the pressure on Iran to show Iran the cost of defying the international community."
The move against IRISL falls under that category and U.S. officials said they also hoped to discourage international companies, especially insurers, from doing business with the line and its affiliates.
"Because of the high risk of unwittingly facilitating Iran's proliferation activities, we call on banks, companies and insurers worldwide to re-evaluate any ongoing relationships with IRISL," said Adam Szubin, the director of Treasury's Office of Foreign Assets Control. "Companies that are providing maritime insurance to a company like IRISL ought to do only after extreme due diligence."
On the Net:
For the list of those designated Wednesday: http://www.ustreas.gov/offices/enforcement/ofac/