LIMA, PERU — President Joe Biden and China’s leader Xi Jinping met for just under two hours on the sidelines of the APEC summit Saturday, marking the end to their 15-year diplomatic relationship and ushering in a new era of uncertainty as Donald Trump prepares to return to office.

The two leaders agreed to avoid giving artificial intelligence control of nuclear weapons systems, and they made progress toward the release of the two U.S. citizens behind bars in China that the State Department considers “wrongfully detained.” Biden also pressured Xi to rein in North Korea’s support of Russia in its conflict with Ukraine.

Biden is looking for ways to emergency-proof the U.S.-China relationship before Trump takes over the White House. And Saturday’s substantive meeting was a sign that both leaders were trying to make the most of Biden’s […]