The United States has imposed sanctions on two North Koreans who have allegedly helped procure equipment and materials for the regime’s missile development program.

The Office of Foreign Assets Control of the U.S. Treasury Department said on Thursday that Choe Chol-min and his wife, Choe Un-jong, who reside in Beijing, were added to its sanctions list.

The Treasury said that Choe Chol-min, a representative of the Beijing office of the Second Academy of Natural Sciences(SANS), has worked with North Korean weapons trading officials and Chinese nationals to purchase and procure materials used in the production of the North’s ballistic missiles.

SANS, Pyongyang’s state organization that conducts research for its ballistic missiles program, is already sanctioned by the U.S. and the UN Security Council(UNSC).

Choe Un-jong reportedly helped coordinate an order with one or more SANS associates for dual-use bearings that are used in North Korean ballistic missile production.

The Treasury said that North Korea uses a network of representatives in foreign countries, including China and Iran, to illegally import restricted materials and components used to create ballistic missiles and other weapons in violation of UNSC resolutions.