"The United States will continue to enforce UN and US sanctions and shut down illicit revenue streams to North Korea," Treasury Secretary Steven Mnuchin said in a statement. "Our sanctions will remain in place until we have achieved the final, fully-verified denuclearization of North Korea."

Agrosoyuz Commercial Bank, registered in Russia, is accused of "knowingly conducting or facilitating a significant transaction" on behalf of Han Jang-su, the Moscow-based chief representative of Foreign Trade Bank, North Korea's main foreign exchange bank.

OFAC also sanctioned Ri Jong-won, the Moscow-based deputy representative of FTB.

Han and FTB are already under US and UN sanctions for their connection to North Korea's WMD programs.

Under UN Security Council Resolution 2321, UN member states are required to expel from their territories any individual who is determined to be working on behalf of or at the direction of a North Korean bank or financial institution.

"Therefore, Han Jang-su and Ri Jong-won should be expelled from Russia," OFAC said in the statement. "Nevertheless, continuing into 2018, Russian bank Agrosoyuz continued to provide services to Han Jang-su, in violation of Russia's UN obligations. Agrosoyuz also knowingly opened multiple bank accounts for at least three FTB front companies. Ri Jong-won also held Russian bank accounts in his name at least as of late 2016."

The sanctions block any property or interests in property of the designated entities and individuals within the US They also prohibit US citizens from conducting transactions with those designated.

The new action also slaps sanctions on two suspected front companies for FTB -- Dandong Zhongsheng Industry & Trade, based in China, and Korea Ungum Corporation, based in Pyongyang. (Yonhap)