For Tim Hsu, who sells modern lamps and ceiling lights mostly to American customers, US President Donald Trump’s historic tariff announcement has upended his carefully made plans. Last year, the Taiwanese businessman decided to invest in Cambodia to diversify his production base beyond his traditional stronghold of south China.

A nonprofit group said the president misapplied a law in imposing those levies and portrayed its filing as the first lawsuit to challenge the Trump administration over its tariffs.