The Justice Department announced Friday that it was seizing more than 500,000 barrels of internationally sanctioned Iranian fuel that officials said was illegally trafficked to provide funding for the country’s paramilitary force.

In addition, prosecutors announced criminal charges related to the sale of the crude oil to buyers in China, Russia and Syria.

Officials described the actions, which come at time of simmering tensions between the U.S. and Iran, as part of a broader effort to disrupt funding to the paramilitary Revolutionary Guard’s Quds Force, an expeditionary unit believed to be working abroad in countries like Iraq, Lebanon, Syria and Yemen to back Iranian-allied militias.