President Donald Trump is ratcheting up the pressure on major drugmakers to bring their US prices in line with the far lower ones available to patients in other countries — though industry experts don’t expect the pharmaceutical companies to acquiesce.

The pharmaceutical industry has long protested the idea of globally linked drug prices as a threat to years of U.S. dominance in biomedical research.

President Donald Trump sent letters to the leaders of 17 major pharmaceutical companies outlining how they should slash U.S. prescription drug prices to match those paid overseas, the White House said on Thursday.