The United States on Thursday sanctioned two Singapore-based firms and an individual over their alleged money laundering for North Korea.

The Department of the Treasury said it is targeting commodities trading company Wee Tiong, marine fuels company WT Marine and Tan Wee Beng, a Singaporean national who serves as the director and a shareholder of Wee Tiong.

It said Tan fulfilled millions of dollars in commodities contracts for North Korea dating back to at least 2011.

Treasury Secretary Steven Mnuchin said in a statement that Tan and his co-conspirators made deliberate efforts to launder money through the U.S. financial system on behalf of North Korea, adding that the U.S. government will not overlook these deceptive practices. 

He said the U.S. is deeply committed to the final, fully verified denuclearization of North Korea, and his department will continue to enforce and implement sanctions until that time.

The move came three weeks after the U.S. slapped sanctions on a Turkish company and two of its officers for trading luxury goods with the North.