The State Department announced Thursday it is imposing sanctions on two unnamed terminal and storage operators of China-based petroleum and crude-oil products who have allegedly facilitated the import of millions of barrels of illicit Iranian oil onboard multiple U.S.-designated tankers.

The agency said the sanctions mark the fourth round of such sanctions on China-based terminal operators "who play a vital role in the trade network for Iranian crude oil that funds Iran’s terrorism abroad and destabilizes the region." 

At the same time, the Treasury Department is sanctioning Greek shipper Antonios Margaritis and his network of companies for allegedly exploiting his status in the oil industry to "illicitly trade in Iranian petroleum," the State Department also said.