The U.S. government has for the first time seized vessels allegedly loaded with Iranian fuel in violation of sanctions imposed by the Trump administration, the Wall Street Journal reported on Thursday, citing U.S. officials.

U.S. prosecutors filed a lawsuit last month to seize the gasoline aboard four tankers that Iran is trying to ship to Venezuela, the latest attempt by the Trump administration to increase economic pressure on the two U.S. foes.

The lawsuit aimed to stop the flow of revenues from oil sales to Iran, which Washington has sanctioned over its nuclear program, ballistic missiles, and influence across the Middle East. Tehran says its nuclear program is for peaceful purposes.

The four vessels, called Luna, Pandi, Bering and Bella, were seized on the high seas in recent days and are now en route to Houston, the WSJ said citing the officials, adding that senior administration officials are expected to meet the tankers at an event scheduled to mark the docking.

The report, citing one official, said the vessels had been taken over without the use of military force, but did not provide any details.