President Donald Trump on Thursday called on the Federal Reserve to take steps to weaken the U.S. dollar — a move that would make American exports more competitive in world markets while increasing prices on imported goods.

"As your President, one would think that I would be thrilled with our very strong dollar. I am not!," Trump wrote in a series of tweets. "The Fed’s high interest rate level, in comparison to other countries, is keeping the dollar high, making it more difficult for our great manufacturers like Caterpillar, Boeing ... John Deere, our car companies, & others, to compete on a level playing field."

Trump's comment break with a long tradition of presidents expressing public support for a strong dollar, which helps keep inflation low and has other advantages, even though it hurts exports.

His comments also come just days after Treasury Secretary Steven Mnuchin formally declared China to be a "currency manipulator" under U.S. law because the People's Bank of China let the yuan weaken beyond 7 to the dollar for the first time in over a decade.

The Treasury Department said it was clear China had acted "to gain an unfair competitive advantage in international trade," a charge that Beijing denied.