SEOUL, South Korea (AP) — South Korean President Moon Jae-in took office four months ago with plans to reach out to North Korea in a way his conservative predecessors did not in the previous decade. Two ICBM launches and one nuclear test later, his government is ramping up its defenses, with some officials even considering asking the United States to bring back tactical nuclear weapons a generation after their removal from the Korean Peninsula.

Seoul's new interest in stronger weapons received a boost Tuesday when the Trump administration agreed to remove previous restrictions on South Korean...