North Korea fired an unidentified ballistic missile into the East Sea on Sunday, the South Korean military said, two days after a US nuclear-powered aircraft carrier arrived in the region for exercises.
The South Korean Joint Chiefs of Staff did not immediately provide any additional details, according to South Korea's Yonhap News Agency.
The launch follows reports that Pyongyang plans to launch a ballistic missile from a submarine.
This is the fifth missile launched by North Korea since the Yoon Seok-yeol administration took office in the southern neighbor last May.
A senior US administration official said on Friday that North Korea may conduct a nuclear test during the visit of US Vice President Kamala Harris to Japan and South Korea, as Pyongyang was preparing for such a test.
The official warned that North Korea would face serious consequences if it chose to carry out the test, according to Yonhap Agency.
In response to a question about the possibility of North Korea conducting a nuclear test during Harris' visit to Japan and South Korea next week, the official said, "It is possible, and we have previously said that North Korea is preparing to conduct a nuclear test."
The US Vice President will pay a four-day visit to Japan, starting next Monday, and will lead a presidential delegation to attend the funeral of former Japanese Prime Minister Shinzo Abe.
Harris will arrive in South Korea next Thursday to meet with President Yoon Sok-yeol, the US official said.