The Yale Budget Lab noted that the letters sent Monday would hike the effective tariff rate on U.S. consumers to the highest since 1934.

Trump and his aides have repeatedly shifted their stance on tariffs since the president’s “Liberation Day” announcement.

Trump delayed the "reciprocal tariffs" in April, vowing to strike roughly 90 trade deals in 90 days. So far, the White House says it has reached trade agreements with only the United Kingdom and Vietnam, as well as a preliminary accord with China.