Inside Biden’s Renewed Promise to Protect South Korea From Nuclear Weapons

WASHINGTON — In the four years since President Donald J. Trump’s leader-to-leader diplomacy with Kim Jong-un of North Korea collapsed after a failed meeting in Hanoi, the North’s arsenal of nuclear weapons has expanded so fast that American and South Korean officials admit they have stopped trying to keep a precise count.

North Korea’s missile tests are so frequent that they prompt more shrugs than big headlines in Seoul.

So when…