Seoul s military said on Sunday that North Korea fired a ballistic missile just days after a United States aircraft carrier arrived for joint drills with the South in a show of force against Pyongyang.
South Korea had earlier detected signs that the North was preparing to launch a submerged ballistic missile SLBM, the president s office said on Saturday a weapon Pyongyang last tested in May.
The Sunday launch is the latest in a record-breaking blitz of weapons tests by nuclear-armed Pyongyang this year, including firing an intercontinental ballistic missile at full range.
In May, the North fired a short range ballistic missile from Sinpo, a major naval shipyard in North Korea.
North Korea fired an unidentified ballistic missile into the East Sea, Seoul s joint chiefs of staff said early on Sunday.
Japan's coast guard also confirmed a likely ballistic missile launch, citing information from Tokyo's defence ministry.
If you spot foreign objects please don't get close to them, but inform the coast guard, the coast guard said.
Japan's public broadcaster NHK said the object appeared to have fallen outside Japan's exclusive economic zone.
South Korea's hawkish president Yoon Suk-yeol, who took office in May, has vowed to beef up joint military exercises with the US after years of failed diplomacy with North Korea under his predecessor.
On Friday, the US Navy's nuclear-powered USS Ronald Reagan aircraft carrier and vessels from its strike group docked in the southern port city of Busan, part of a push by Seoul and Washington to have more US strategic assets operating in the region.
Yoon is going to meet US Vice President Kamala Harris on Thursday when she visits Seoul this week after a visit by President Joe Biden in May and US House Speaker Nancy Pelosi last month.
The USS Reagan will take part in joint drills off South Korea's east coast this month.
Washington is Seoul's key security ally and has around 28,500 troops in South Korea to protect it from the North.
The two countries have long carried out joint exercises they insist are purely defensive, but North Korea sees them as rehearsals for an invasion.
Pyongyang could be making a show of strength, while a US aircraft carrier is visiting South Korea for defence exercises, said Leif-Eric Easley, professor at Ewha University in Seoul.
North Korea's major tests are the result of a long-term campaign for advancing military capabilities. South Korean and US officials have been warning for months that the North Korean leader, Kim Jong-un, is preparing to conduct another nuclear test.
The isolated regime has tested nuclear weapons six times since 2006. Pyongyang claimed that it was a hydrogen bomb in 2017 and that it had an estimated yield of 250 kilotons.
Easley said that North Korea might be delaying its seventh nuclear test out of respect for China's upcoming political conference that Xi Jinping is tightly scripting to extend his leadership.
There are limits to Pyongyang's self-restraint.