President Donald Trump on Friday accused China of "totally" violating the preliminary trade agreement signed earlier this month, reigniting tensions between Washington and Beijing and triggering a drop in U.S. stock futures. The charge came as signs mounted that talks to extend the fragile 90-day tariff truce were faltering.

"The bad news is that China, perhaps not surprisingly to some, HAS TOTALLY VIOLATED ITS AGREEMENT WITH US. So much for being Mr. NICE GUY!" Trump posted on Truth Social. He claimed the U.S. had paused tariffs in good faith, while China had failed to uphold its end of the May 12 deal.

The accord, reached during negotiations in Switzerland, had suspended most reciprocal tariffs and reduced U.S. duties on Chinese imports from 145% to 30%. But according to the president and senior officials, Beijing has not fulfilled its commitments, throwing the future of the agreement into doubt.

U.S. Trade Representative Jamieson Greer, speaking on CNBC Friday morning, backed Trump's assessment. "We're very concerned with" China's purported non-compliance, Greer said. The "United States did exactly what it was supposed to do, and the Chinese are slow rolling their compliance." He added that the situation is "completely unacceptable and has to be addressed."

Stock futures reacted swiftly to the president's post, with S&P 500 futures falling around 0.5%. The index had been climbing steadily, up nearly 5% since the May 12 deal was announced, in part due to optimism that Trump would hold back further tariff escalations.

Treasury Secretary Scott Bessent said Thursday that trade talks with China "are a bit stalled," confirming earlier reports of growing friction. The Chinese embassy in Washington did not immediately respond to requests for comment.

Trump claimed that prior to the May 12 agreement, China was on the verge of economic collapse due to the heavy tariff burden imposed by the U.S. "Two weeks ago China was in grave economic danger!" he wrote. "The very high Tariffs I set made it virtually impossible for China to TRADE into the United States marketplace."

"I made a FAST DEAL with China in order to save them from what I thought was going to be a very bad situation," Trump added. "Because of this deal, everything quickly stabilized and China got back to business as usual."

Now, with the agreement allegedly in breach, the administration is signaling that retaliation may be forthcoming, although specific next steps have not been disclosed. The existing tariff pause is scheduled to remain in effect until August 12.

Meanwhile, the broader legal foundation of Trump's tariff strategy faces its own challenges. A federal court recently ruled that the administration overstepped its authority in imposing certain tariffs, though the decision has been temporarily stayed pending appeal.