Wall Street futures sank and the safe-haven yen and Swiss franc strengthened early on Monday as building deflationary pressures in China added to growth worries from a fading U.S. economy and an escalating global trade war.

Trump’s acknowledgment of economic turbulence was a reversal from previous cheering of his policies, and it contrasted with reassurances from his own advisers Sunday.

While tariffs shock investors into risk-off mode, markets are also questioning other parts of Trump's agenda that were meant to be a boost to stocks.

Wall Street's main stock indexes tumbled late Monday to end sharply lower after President Donald Trump announced the start of 25% tariffs on Canada and Mexico.

President Donald Trump teased that tariffs could climb higher over time while responding to Maria Bartiromo's questions about business leaders' desire for predictability.