
Just days after a nuclear-powered US aircraft carrier arrived at a South Korea port ahead of joint military training, North Korea launched an unidentified ballistic missile into the East Sea on Sunday, according to the South Korean military.
The Joint Chiefs of Staff in Seoul stated early on Sunday that "North Korea fired an unidentified ballistic missile" without providing any other information.
The launch, which is a part of the North's record-breaking barrage of weapons tests this year, came after rumours suggested Pyongyang might be getting ready to launch a ballistic missile from a submarine.
Citing information from Tokyo's defence ministry, the Japanese coast guard also confirmed the possibility of a ballistic missile launch and alerted ships to the situation.
The coast guard advised ships to keep an eye out for any fresh information and to report any alien objects rather than approaching them.
The item looked to have fallen outside of Japan's exclusive economic zone, according to official broadcaster NHK in Japan.
In line with Seoul and Washington's efforts to increase the number of US strategic assets operating in the region, the nuclear-powered USS Ronald Reagan and ships from its strike group berthed in the southern port city of Busan on Friday.
After years of unsuccessful negotiation with North Korea under his predecessor, South Korea's hawkish President Yoon Suk-yeol, who took office in May, has vowed to increase joint military drills with the United States.
This month, the USS Reagan will take part in joint exercises off the east coast of South Korea.
About 28,500 US troops are stationed in South Korea as Washington, Seoul's main security ally, guards the country from the North.
The two nations have long engaged in cooperative drills, which they maintain are only defensive in nature but which North Korea interprets as invasion drills.
For months, North Korean leader Kim Jong Un has been the subject of warnings from South Korean and US officials.
(with inputs from agencies)