New York. Wall Street’s months-long calm shattered Friday as US stocks tumbled after former President Donald Trump threatened to impose even higher tariffs on Chinese imports.

The S&P 500 fell 1.5 percent, on track for its sharpest loss since Aug. 1. The Dow Jones Industrial Average slid 456 points, or 1 percent, as of 11:35 a.m. Eastern time, while the Nasdaq composite dropped 2.2 percent.

Stocks had been heading for modest gains earlier in the day until Trump posted on his social media platform that he was considering “a massive increase of tariffs” on Chinese goods. He expressed anger over China’s restrictions on exports of rare earth materials, which are vital for products ranging from electronics to jet engines.

“We have been contacted by other countries who are extremely angry at this great trade hostility, which came out of nowhere,” Trump wrote on Truth Social. He added that he saw “no reason” to meet with Chinese President Xi Jinping during his upcoming trip to South Korea.

The renewed trade tensions between the world’s two largest economies triggered a broad sell-off, with roughly three out of every four S&P 500 stocks falling.

Levi Strauss plunged 12.3 percent, one of the market’s steepest declines, despite reporting quarterly earnings that topped analyst expectations. While its full-year profit forecast was in line with estimates, the apparel company may be struggling against lofty investor expectations after its shares surged nearly 42 percent this year.

More broadly, analysts have warned that US equities have become overvalued after prices rose much faster than corporate earnings, particularly among companies tied to artificial intelligence. The S&P 500 has climbed about 35 percent since an April low, though momentum has slowed recently.

A renewed US government shutdown has also delayed key economic reports that typically guide investors, adding to uncertainty.

Oil prices sank as well. Benchmark U.S. crude fell 3.6 percent to $59.27 a barrel after a ceasefire between Israel and Hamas took effect in Gaza, raising hopes for reduced tensions in the Middle East. Brent crude, the international benchmark, declined 3.3 percent to $63.08.

In the bond market, the yield on the 10-year Treasury dropped to 4.06 percent from 4.14 percent late Thursday.

Overseas, stock indexes mostly declined. Hong Kong’s Hang Seng lost 1.7 percent, Japan’s Nikkei 225 fell 1 percent, while South Korea’s Kospi jumped 1.7 percent as markets reopened following a holiday.