President-elect Donald Trump said he would require countries that are part of BRICS — a China- and Russia-backed group of emerging economies — to commit to not creating new currency or face 100% tariffs during his administration.

Trump is threatening 100% tariffs against a bloc of nine nations including Brazil, Russia, India, China and South Africa if they act to undermine the U.S. dollar.

While China could offset American tariffs by letting its currency fall, that might endanger Beijing’s recent efforts to stabilize the economy.