The Biden administration imposed new tariffs to stop certain countries from evading U.S. tariffs on steel and aluminum by routing products through Mexico.

As part of an agreement with Mexico, steel products imported through the country must be melted and poured in North America otherwise they will be subject to a 25% U.S. “Section 232” tariff; and a 10% tariff on aluminum.

The new aluminum tariffs apply to products smelt or cast in China, Russia, Belarus or Iran.

Importers of the products to the U.S. will need to provide documentation showing the country of origin for the metals, Biden administration officials told Reuters.

“The financial impact of the tariffs is likely somewhat modest, though, given the volumes of steel and aluminum being routed this way through Mexico,” AP reported.