Its Department of Commerce said in a statement Tuesday it had found cold-rolled steel and corrosion-resistant steel products only superficially processed in Vietnam after being shipped from South Korea and Taiwan.

It had slapped duties on South Korean products in 2015 and Taiwanese products in 2016.

Since those dates through April 2019, shipments of corrosion-resistant steel products and cold-rolled steel from Vietnam to the U.S. increased by 332 percent and 916 percent, the statement said.

The inquiry was initiated at the demand of steel companies like ArcelorMittal SA’s, Nucor Corp and United States Steel Corp.

In May last year the U.S. had slapped duties on some Vietnamese steel products it claimed originated in China.

The Donald Trump administration has so far issued 31 anti-circumvention determinations, a 417 percent increase compared to the previous administration in the comparable period.