Pressure is building for South Korea to build its own nuclear bomb, a bad sign for stability in Asia and for anyone hoping to keep nuclear weapons from spreading.

• Trump abruptly cut back a big joint US–South Korea military exercise with no warning to Seoul, saying it was hostile toward North Korea.
• The move looks like punishment: Trump has complained that South Korea refused to help with the war on Iran while America defends it from Kim Jong-un.
• North Korea gave nothing in return, saying it has no plan to negotiate and no desire to give up its nuclear weapons.
• South Korean lawmakers, newspapers, and about 70% of the public now back getting the bomb, and experts think Seoul could build one in one to three years.
• Washington has also pulled missile defenses and its last aircraft carrier out of the region for the Middle East, leaving Asia thinly covered.

Outlook: If Seoul moves ahead, Japan may follow, opening the door to a nuclear arms race across Asia.