North Korea fires more than 20 missiles, one close to South

One of the missiles landed in waters just 57 kilometres east of the mainland, the military said, calling the incident "very rare and intolerable".

North Korea fired more than 20 missiles on Wednesday, including one that landed close to South Korea's waters in what President Yoon Suk-yeol said was "effectively a territorial invasion".

It also fired an artillery barrage into a maritime "buffer zone" that experts said was part of an "aggressive and threatening" response by Pyongyang to large-scale joint air drills the United States and South Korea are conducting.

One short-range ballistic missile crossed the Northern Limit Line, the de facto maritime border, prompting a rare warning for residents on the island of Ulleungdo to seek shelter in bunkers.

Seoul's military said it was the "first time since the peninsula was divided" at the end of Korean War hostilities in 1953 that a North Korean missile had landed so close to the South's territorial waters.

"President Yoon pointed out today that North Korea's provocation is an effective territorial invasion by a missile," his office said in a statement.

One of the missiles landed in waters just 57 kilometres east of the mainland, the military said, calling the incident "very rare and intolerable".

Pyongyang fired a total of 23 missiles including seven short-range ballistic missiles and six ground-to-air ones, Seoul's military said.