North Korea fired an unspecified ballistic missile toward the east coast on Sunday, South Korea's Joint Chiefs of Staff said.
The projectile appears to have landed outside of Japan's exclusive economic zone (EEZ), according to Japanese public broadcaster NHK.
The launch came as a US aircraft carrier arrived in South Korea to participate in joint drills with South Korean forces, and days before a planned visit next week by US Vice President Kamala Harris.
A senior US administration official told a briefing on Friday that a nuclear test or other provocation was possible during Harris’ trip to the region, but that they had no predictions or announcements to make.
The purpose of the trip is to “reaffirm the United States’ commitment to our allies in an increasingly complex security environment” and to “deepen our overall engagement in the Indo-Pacific” in addition to honouring the former prime minister, said officials.
The visit comes after US President Joe Biden accused North Korea of “blatantly violating UN sanctions” in a speech to the UN General Assembly on Wednesday, citing the country as among the reasons to strengthen international nuclear non-proliferation efforts.
Analysts first spotted signs that at least one new submarine was being built in 2016, and in 2019 state media showed North Korean leader Kim Jong-un inspecting a previously unreported submarine that was built under "his special attention" and that would be operational in the waters off the east coast.
State media at the time did not describe the submarine's weapons systems or say where and when the inspection took place, but analysts said the apparent size of the new vessel indicated it was designed to carry missiles.
North Korea has a large submarine fleet but only one known experimental submarine capable of carrying a ballistic missile.
Analysts have debated whether the apparent new missile submarine is a new design, or whether it is based on a modified Romeo Class of submarine originally acquired from China in the 1970s before North Korea began producing them domestically.
Earlier this year, North Korea test-fired a submarine-launched ballistic missile (SLBM) in May from near Sinpo, where North Korea keeps submarines as well as equipment for test-firing SLBMs.
