SEOUL: A North Korean ballistic missile reportedly landed less than 60 kilometres off the coast of South Korea on Wednesday. South Korea responded with a missile launch of its own, officials said.

This is the first time a missile has landed near the South Korean Sea.

The missile landed outside of South Korea's territorial waters, but south of the Northern Limit Line (NLL), a disputed inter-Korean maritime border in what South Korean President Yoon Suk-yeol called an "effective act of territorial encroachment."

South Korean warplanes fired three air-to-ground missiles into the sea north across the NLL in response, the South's military said.
The South's launches came after Yoon's office vowed a "swift and firm response" so North Korea "pays the price for provocation".

The North Korean weapon was one of three short-range ballistic missiles fired from the North Korean coastal area of ​​Wonsan into the sea, South Korea's Joint Chiefs of Staff (JCS) said. The JCS later said as many as 10 missiles of various types had been fired from North Korea's east and west coasts.

"We heard the siren around 8:55 a.m. and all of us in the building went down to the evacuation area in the basement," an Ulleng County official told the media.

A resident on the south side of the island said no warnings had been received.

Nuclear-armed North Korea has tested a record number of missiles this year, and officials in Seoul and Washington say North Korea has completed technical preparations to conduct its first nuclear test since 2017.

Despite Yoon's declaring a national week of mourning after more than 150 people were killed in a weekend crowd surge in Seoul, the United States and South Korea began one of their largest combined military air drills on Monday.

Dubbed Vigilant Storm, the exercise involves hundreds of fighter jets from both sides carrying out 24-hour mock strikes.

North Korea had said that a recent flurry of launches was in response to allied drills.

Pak Jong Chon, secretary of the Central Committee of North Korea's ruling Workers' Party, said in a statement on Wednesday that the number of warplanes involved in Vigilant Storm proved the exercise was "aggressive and provocative" and specifically targeted North Korea. He said even its name imitated the U.S.-led Operation Desert Storm against Iraq in the 1990s.

A spokesman for the South Korean military said authorities were analyzing the launches to see whether the missiles' flight paths were intentional or whether one had gone off course.

Japan defence minister Yasukazu Hamada said the government believed at least two ballistic missiles had been launched from North Korea, one flying east and another southeast.

It was the first time a North Korean ballistic missile had landed near South Korean waters, JCS said.

North Korea's actions threaten the peace and stability of Japan, the wider region, as well as the broader international community, and are utterly unacceptable, Hamada said.