In this July 26 file photo, U.S. Secretary of State Mike Pompeo stands in the Oval Office of the White House in Washington. AP

The United States on Monday sanctioned a Vietnam-based North Korean on suspicion of supporting North Korea's weapons of mass destruction program in violation of U.N. sanctions.

The U.S. Treasury Department announced the measure on its website, saying the individual, Kim Su-il, is tied to the North's ruling Workers' Party and an employee of its affiliate, the Munitions Industry Department.

That department, it said, was previously sanctioned by the U.S. and the U.N. for its involvement in "key aspects" of North Korea's missile program.

"Treasury continues to enforce existing sanctions against those who violate United Nations Security Council resolutions (UNSCRs) and evade U.S. sanctions on North Korea's unlawful nuclear and ballistic missile programs," Treasury Under Secretary for Terrorism and Financial Intelligence Sigal Mandelker said. "Kim Su Il has violated UNSCRs and supports North Korea's weapons program."