BEIJING — China said Sunday it wouldn’t step up its purchases of American products if President Donald Trump goes ahead with his threat to tax billions of dollars’ worth of Chinese imports. White House advisers insisted on fundamental changes in ties between the world’s two biggest economic powers.

China’s warning came after delegations led by U.S. Commerce Secretary Wilbur Ross and China’s top economic official, Vice Premier Liu He, wrapped up a meeting on Beijing’s pledge to narrow its trade surplus. Ross said at the start of the event they had discussed specific American exports China might purchase, but the talks ended with no joint statement and neither side released details.

“Both sides appear to have hardened their negotiating stances and are waiting for the other side to blink,” said Eswar Prasad, professor of trade policy at Cornell University. “Despite the potential negative repercussions for both economies, the risk of a full-blown China-U.S. trade war, with tariffs and other trade sanctions being imposed by both sides, has risen significantly.”