Chinese President Xi Jinping, while meeting with President Donald Trump in Beijing overnight, warned there would be “clashes” and “conflicts” over Taiwan if the United States does not handle the regional dispute well.

China has claimed sovereignty over Taiwan for years, while the U.S. has backed the self-governing island’s military capabilities through arms sales and strategic planning in the event of a possible invasion from mainland China. Despite the aid, the U.S. does not officially recognize Taiwan’s independence. The issue threatens to derail the U.S.-China relationship.