Washington on Wednesday announced new import duties on more than $1 billion in imported structural steel from China and Mexico, saying manufacturers in those countries dumped product on the US market.

The Commerce Department’s findings, which are preliminary and could be reversed, follow a similar decision in June concerning Chinese alloy aluminum imports valued at nearly $1 billion.

Chinese and Mexican producers allegedly dumped fabricated structural steel — such as I-beams, rods and joists — at margins of between 0 percent and 141.4 percent, the Commerce Department said.

The department said it had rejected such allegations concerning similar products from Canada, however.

The findings were the result of a complaint lodged in February by members of the American Institute of Steel Construction in Chicago.

The decision comes after President Donald Trump in May agreed to lift punitive duties on steel from Mexico, which joined the United States and Canada in negotiating a new North American trade pact last year.

Last year, Mexican and Chinese imports of structural steel were together valued at $1.6 billion.

A final determination by the Commerce Department is due early in 2020.

If the preliminary findings are upheld, the duty increases could still be reversed by the US International Trade Commission, which examines whether the imports have harmed a US industry.