President Donald Trump (L) and Russia's President Vladimir Putin during a meeting at the Presidential Palace in Helsinki, July 16, 2018.

The Russian-registered bank AgrosoyuzCommercial Bank (Agrosoyuz) was sanctioned for doing business with Han Jang Su, a North Korean who Treasury said was the "Moscow-based chief representative of Foreign Trade Bank (FTB), North Korea's primary foreign exchange bank."

The new sanctions, announced by the Treasury Department, came as President Donald Trump continued to pursue negotiations with North Korean leader Kim Jong Un to denuclearize the Korean Peninsula, as well as seeking improved relations with Russia.

The Trump administration on Friday announced new sanctions targeting a Russian bank, two North Korean entities and one North Korean citizen for facilitating "illegal financial activity."

Han is already designated under existing sanctions, but Treasury also sanctioned his deputy, Ri Jong Won, Friday.

The two newly sanctioned North Korean entities, DandongZhongsheng Industry & Trade Co., Ltd. (Zhongsheng), and Korea Ungum Corporation(Ungum), were both described in the Treasury announcement as front companies for FTB, the North Korean bank.

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

The Wall Street Journal reported earlier this week that North Korean workers were continuing to flow into Russia, in spite of UN sanctions intended to block cash from flowing back to North Korea.

The announcement came one day after Trump publicly thanked Kim for returning the remains of U.S. soldiers killed in the Korean War. The president said he looked forward to seeing the North Korean leader again "soon."

Trump tweet