When U.S. President Joe Biden and Chinese President Xi Jinping meet for four hours on Wednesday before the Asia-Pacific Economic Cooperation Leaders’ Meeting in San Francisco, there will be much to discuss.

In addition to Russia’s war on Ukraine, tensions over Taiwan and the ongoing confrontation in the South China Sea, the Israel-Hamas conflict and how to keep it from escalating will be high on the agenda. So, time will be short and the discussions will be difficult, but one important topic should not be missed: North Korea.

In the past, U.S.-China summits often focused on how to head off the danger posed by North Korea’s growing and increasingly sophisticated arsenal of nuclear weapons and ballistic missiles. One U.S. administration after another — Republican and Democratic alike — believed the road to achieving America’s ultimate objective, North Korea’s denuclearization, ran through China, the North’s patron. All were disappointed, although all found some common ground that helped manage the threat, as well as uncontrolled tensions that could lead to a second Korean war.