This undated photo shows a firing of a weapon an undisclosed location in North Korea. AP

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

The 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.

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"President Yoon pointed out today that North Korea's provocation is an effective territorial invasion by a missile that crossed the Northern Limit Line for the first time since the division," his office said in a statement.

The missile closest to South Korea landed in waters just 57 kilometres (35 miles) east of the mainland, the military said.

The military released a statement describing the launch near the South's territorial waters as "very rare and intolerable".

"Our military vowed to respond firmly to this (provocation)," it added.

South Korea President Yoon Suk-yeol speaks during an event. File photo

Soon after, the South Korean military said it had fired three air-to-ground missiles at the same spot on the maritime border where the North Korean one had landed.

An air raid warning was issued for Ulleungdo after the North Korean missile launch. The alert was flashed on national television and told residents to "evacuate to the nearest underground shelter".

The South Korean military's Joint Chiefs of Staff initially said it detected the launch of three short-range ballistic missiles.

But it later announced North Korea had fired more than 10 missiles "of various types today towards the east and west".

Yoon Suk-yeol called a meeting of the National Security Council over the launches, ordering "swift and stern measures so that North Korea's provocations pay a clear price."

Japan also confirmed the North Korean missile launches, with Prime Minister Fumio Kishida telling reporters he planned to call a "national security meeting as soon as possible."

South Korea closed some air routes over the East Sea, also known as the Sea of Japan, advising local airlines to detour to "ensure passenger safety in the routes to the United States and Japan".

Agence France-Presse