South Korea's Joint Chiefs of Staff said that from 3.30 to 3.46 am North Korea fired two short-range ballistic missiles from an area near capital Pyongyang that flew about 550 kilometres before landing in waters east of the Korean Peninsula.
Those flight details were similar to the assessment of the Japanese military, which said the missiles landed outside of Japan's exclusive economic zone and that there were no immediate reports of damage from ships or aircraft in affected areas.
The flight distance of the North Korean missiles roughly matched the distance between Pyongyang and the South Korean port city of Busan, where the USS Kentucky arrived on Tuesday afternoon in the first visit by a US nuclear-armed submarine to South Korea since the 1980s.
Japanese Defence Minister Yasukazu Hamada told reporters that the North Korean missiles travelled on a low trajectory, with their maximum altitude reaching about 50 kilometres, and possibly demonstrated "irregular manoeuvre" in flight.
Japan has previously used similar language to describe the flight characteristics of a North Korean weapon modelled after Russia's Iskander missile, which travels at low altitudes and is designed to be manoeuvrable in flight to improve its chances of evading missile defences.
Wednesday's launches marked the North's first ballistic activity since July 12, when it flight-tested a new solid-fuel intercontinental ballistic missile that demonstrated potential range to reach deep into the US mainland. That launch was supervised by the country's authoritarian leader Kim Jong Un, who vowed to further bolster his country's nuclear fighting capabilities in the face of expanding US-South Korean military activities, which he blamed for worsening the security environment on the Korean Peninsula.
Periodic visits by US nuclear ballistic missile-capable submarines to South Korea were one of several agreements reached by the two countries’ Presidents in April in response to North Korea’s expanding nuclear threat. They also agreed to establish a bilateral Nuclear Consultative Group and expand military exercises.
The USS Kentucky, an Ohio-class submarine, arrived at the South Korean port of Busan on Tuesday afternoon, South Korea’s Defence Ministry said. It is the first visit by a US nuclear-armed submarine to South Korea since the 1980s, it said.
Defence Minister Lee Jong-Sup called the submarine’s visit a demonstration of US resolve in implementing its “extended deterrence” commitment, a pledge by the US to use its full military capabilities, including nuclear weapons, to protect its allies, the ministry said in a statement. He said the submarine’s visit “shows the allies’ overwhelming capability and posture against North Korea”.