U.S. Trade Representative Robert Lighthizer on Thursday defended the Trump administration’s use of national security as the premise for tariffs on products like steel and aluminum, even in cases where the products were coming from long-term allies of the U.S.

“If you are of the opinion that the section 232 [of the Trade Expansion Act] is justified because of the need to preserve the U.S. steel industry, then you have to put in place a program that actually works,” Lighthizer told the Senate Appropriations Committee Thursday. “That means every country has to be [included]. You can’t let all of the steel come through any other country. Otherwise the program doesn’t make any sense.”