The Trump administration expanded economic sanctions against Iran on Tuesday as it also resumed a naval blockade of Iranian ports, oil terminals, and coastal areas.

The Treasury Department's Office of Foreign Assets Control announced new sanctions on the network of shipping magnate Hossein Shamkhani, the leader of a business empire that the department alleges facilitates strategically significant oil and arms deals for Tehran and Moscow.

In total, OFAC sanctioned more than 50 individuals, entities, and vessels that it said in a news release enabled Shamkhani and the Iranian regime "to continue profiting while the Iranian people remain burdened under the economic yoke imposed by their government."

The Treasury Department said it has now sanctioned more than 200 individuals, entities, and vessels operating under Shamkhani's patronage.

"The Iranian regime survives on deception, and the Shamkhani network is one of its most profitable engines," Treasury Secretary Scott Bessent said in a statement. "Treasury is shutting down the financial infrastructure that allows the regime to continue its threats to U.S. national security and global shipping."

Bessent also said in a post on X that OFAC "sanctioned multiple wallets tied to the Central Bank of Iran, resulting in the freeze of over $130 million. We will continue to aggressively follow the money and deny the Iranian regime access to the proceeds of its illicit revenue schemes."

The sanctions and the resumption of the blockade are part of the Trump administration's strategy to exert military and economic pressure on Iran following the collapse of a memorandum of understanding signed by the two sides last month.

The MOU established a 60-day period for negotiations to continue toward a final peace agreement. But it collapsed following Iranian attacks on commercial vessels in the Strait of Hormuz and retaliatory U.S. strikes.

The Iranian attacks led the U.S. on July 7 to revoke a waiver that allowed new sales of Iranian oil. Three days later, it imposed new sanctions, including measures targeting Supreme Leader Mojtaba Khamenei's financing network.