North Korea fired a ballistic missile off its east coast towards Japan early on Wednesday, Seoul’s military said, days before the planned start of massive US-South Korea joint drills.

The 11-day exercises due to begin on Monday are a regular fixture of the summer calendar, designed to steel the United States and South Korea for defense against the nuclear-armed North.

Pyongyang calls them rehearsals for an invasion and has staged missile launches before and after them in the past.

“Our military detected at around 6:00 am (2100 GMT on Tuesday) a ballistic missile launched by North Korea from the Wonsan area towards the East Sea,” Seoul’s Joint Chiefs of Staff said in a message to reporters.

The missile flew more than 700 kilometers (435 miles) over the body of water — also known as the Sea of Japan — it said, adding that Seoul and Washington were analyzing its specifications.

Japan’s Defense Ministry also described the object as a suspected ballistic missile, adding that it was thought to have “already fallen”, without providing further details.

Japan’s Defense Minister Shinjiro Koizumi called Wednesday’s launch a “threat to peace and security in our region” and said Tokyo had “lodged a strong protest” with North Korea through diplomatic channels in Beijing.

North Korea has recently been hurling criticism at Japan, a former regional colonial power, over what Pyongyang describes as its remilitarization.

South Korea’s national security office convened an emergency meeting on Wednesday, where participants called recent launches “provocative acts” and demanded Pyongyang “immediately halt them”.

North Korea has been playing a more active role in international conflict, notably backing Russia in its invasion of Ukraine.

Ukraine accused Russia on Tuesday of launching North Korean missiles in an attack that killed 10 and wounded dozens.

Ukrainian President Volodymyr Zelensky has also warned — without providing evidence — that Moscow has been receiving more ballistic projectiles and troops from Pyongyang.

Experts say North Korea has received financial and military benefits from Moscow in return for its support. Its troops have also gained crucial experience on modern battlefields.

The US-South Korea “Ulchi Freedom Shield” drills due on Monday will include 18,000 South Korean troops and counterparts from the US contingent of 28,500 in the country.

A spokesman said they will prepare soldiers for a potential fight against North Korean troops battle-hardened from deployment in Europe. (AFP)