The U.S. is refusing to resume trade negotiations with China until Beijing comes up with a concrete proposal to address Washington’s complaints about forced technology transfers and other economic issues, officials on both sides of the Pacific said.

The impasse threatens to undermine a meeting between President Trump and President Xi Jinping of China that is scheduled for the end of November at the Group of 20 leaders summit in Buenos Aires. Both sides had hoped the gathering would ease the trade tensions. U.S. businesses have been counting on sufficient progress at the meeting for the Trump administration to suspend its plan to increase tariffs on $200 billion of Chinese imports to 25% on Jan. 1, from the current 10%. Such a move would be a blow to U.S. importers and consumers.

Negotiations have been on hold since mid-September, when the Chinese canceled a trip to Washington after the U.S. announced levies on the $200 billion of Chinese imports. Since then, Beijing has sought to re-engage, including asking U.S. Treasury Undersecretary David Malpass to resume talks. He declined—with the backing of the White House trade team—until the Chinese present a formal offer, U.S. officials said.

“If China wants [the G-20 session] to be a meaningful meeting, we need to do the groundwork,” a senior White House official said. “And if they don’t give us any information, it’s just hard to see how that becomes fruitful.”