President Donald Trump announced Thursday that he has urged 17 major pharmaceutical companies to cut U.S. drug prices within 60 days, threatening aggressive action if they fail to comply.

In letters to companies like Pfizer, Merck, and Johnson & Johnson, Trump demanded they offer Americans the same low prices they provide in other developed countries, particularly for Medicaid and Medicare patients.

He also called for direct-to-consumer pricing models and tougher negotiations with foreign governments.

The move follows his revival of the “most favored nation” policy to tie U.S. drug prices to international rates, CNBC has reported.

Drugmaker stocks fell after the announcement, and industry leaders expressed concern, warning that foreign price controls could harm innovation.

Written by B.C. Begley