The leaders agreed that humans should control decisions to use nuclear weapons — not AI. And they talked about the importance of stability during the transition to a new U.S. administration.

Chinese President Xi Jinping warned President Biden not to cross four “red lines” regarding Taiwan and the communist system as the outgoing president called for continued communications.

Donald Trump has made a tougher stance toward China central to his pitch on foreign policy, even as Joe Biden and Xi Jinping sought to lower tensions before the next president takes office.