SEOUL, South Korea (AP) — North Korea confirmed Thursday it has carried out its first underwater-launched ballistic missile test in three years, in an apparent bid to dial up pressure on the United States ahead of a weekend resumption of their nuclear diplomacy.

Wednesday’s test of the Pukguksong-3 missile, which North Korea describes as a submarine-launched ballistic missile, is seen as the North’s most high-profile weapons launch since it began diplomacy with the United States early last year. Some experts say North Korea wants to show to the U.S. what would happen if diplomacy fails again....