South Korea has detected signs that North Korea is preparing to launch a ballistic missile from a submarine, the South Korean presidential office said Saturday.
The North has repeatedly conducted ballistic missile tests since the start of this year.
The move came a day after the United States aircraft carrier Ronald Reagan arrived in the South Korean port city of Busan for the first time in nearly five years to join naval exercises.
It is rare for the presidential office to announce signs of North Korea preparing for a possible missile launch, with such information usually released by the country's military.
The announcement came as concerns mount that North Korea may be about to conduct what would be its seventh nuclear test and first since 2017.
