President Trump on Monday posted a barrage of letters he sent to country leaders, saying he would impose an array of tariffs similar to levels he announced in April. The most significant were letters to the leaders of Japan and South Korea that informed them of 25% tariffs on imports from their respective countries.

The leaders of Japan and South Korea were the first to get letters on Monday that informed them of the new tariff rates.

Legal challenges to Trump’s ability to implement tariffs unilaterally are further extending the cloudy outlook for tariff policy and could result in a reversal of some of the duties already in place.