The U.S. has sanctioned two individuals and three companies linked to them for helping smuggle oil into North Korea, the Treasury Department said Friday, marking Washington’s latest effort to throttle the flow of fuel into the country.

According to a Treasury press release, Singapore-based Kwek Kee Seng and Taiwan-based Chen Shih Huan brokered several shipments of refined oil for the DPRK between 2019 and 2021, which the Treasury says “directly supports” North Korea’s military.