The U.S. Treasury Department, in coordination with the United Kingdom, is clamping down harder on Russia’s ability to wage war against Ukraine by banning the import of Russian-origin aluminum, copper, and nickel.

The world’s two largest metal exchanges, the London Metal Exchange and the Chicago Mercantile Exchange, will no longer trade in new aluminum, copper, and nickel produced by Russia, the Treasury announced in a press release Friday. To implement the new policy, the Treasury issued two new determinations that will be enforced by its Office of Foreign Assets Control (OFAC).