WASHINGTON (AP) — The United States on Friday imposed sanctions on a fleet of nine ships and their owners accused of transporting hundreds of millions of dollars in forbidden Iranian oil to foreign markets.

The sanctions are being imposed because of Iran’s “shutdown of internet access to conceal its abuses” against its citizens during its crackdown on nationwide protests, the U.S. Treasury Department said. They “target a critical component of how Iran generates the funds used to repress its own people,” Treasury Secretary Scott Bessent said.

Iranians and Iranian businesses have been struggling under the longest and most comprehensive internet shutdown in the history of the Islamic Republic. The government blocked internet access on Jan. 8 as nationwide protests led to a crackdown on information sharing.

The Treasury’s Office of Foreign Assets Control said the nine targeted vessels — flagged from Palau, Panama and other jurisdictions — are part of a shadow fleet, a network of older tankers used to transport goods that are subject to international sanctions, notably from Russia and Iran. The U.S. sanctions aim to prevent the targeted Iranians from doing business with Americans or accessing U.S. accounts.

Friday’s action is part of an ongoing buildup of tensions between the U.S. and the theocratic nation as an American aircraft carrier group inches closer to the Middle East. President Donald Trump called the group an “armada” in comments to journalists aboard Air Force One late Thursday.

Trump added that the U.S. was moving the ships toward Iran “just in case” he wants to take action against Iran’s government. The Republican president has repeatedly boasted that his threats on Iran have prevented the execution of more than 800 dissidents.

Iran’s top prosecutor on Friday called Trump’s repeated claims “completely false.”

Meanwhile, the death toll in Iran from the bloody crackdown on nationwide demonstrations rose to at least 5,032, activists said.

The U.S. issued sanctions this month against Iranian officials and firms accused of helping to repress the nationwide protests, which challenged Iran’s theocratic government, including the secretary of the Supreme Council for National Security, whom the Treasury accuses of being one of the first officials to call for violence against protesters.

Trump on Thursday declined to say whether the Supreme Leader Ayatollah Ali Khamenei should be removed from office.