NEW YORK -- US President Donald Trump on Thursday imposed a 100 percent ad valorem tariff on imports of certain patented pharmaceuticals and associated pharmaceutical ingredients.

In an executive order signed Thursday, Trump said such imports are "in such quantities and under such circumstances as to threaten to impair the national security of the United States."

The tariffs imposed will be effective on or after 12:01 am eastern daylight time on July 31, 2026.

The tariffs will be 20 percent for products of companies that have, or that are likely soon to have, onshoring plans approved by the U.S. secretary of commerce, but will increase to 100 percent on April 2, 2030, the order said.

Japan, the European Union, the Republic of Korea, and Switzerland and Liechtenstein jointly which have struck trade deals with the US will face a 15 percent tariff, and Britain will face a 10 percent tariff, according to the order.

Generic pharmaceutical products, biosimilars and related ingredients have been exempted from tariffs at this time, including nuclear medicines, plasma derived therapies, fertility treatments, and cell and gene therapies, the order said.