Seoul has said North Korea fired more than ten missiles off its eastern and western coasts hours after issuing a veiled threat to use nuclear weapons against the US and South Korea.

The escalation in animosities between the rivals saw South Korea issue an air raid alert for an eastern island, with residents there evacuated to underground shelters.

After the North fired the missiles in its direction on Wednesday morning, South Korea quickly responded by performing its own missile tests.

Seoul said it conducted the air-to-surface missile tests to show its determination to get tough on North Korean provocations. South Korea’s military said its fighter jets fired three precision-guided missiles to sites near the rivals’ eastern sea border.

In an emergency meeting with top security officials, South Korean President Yoon Suk Yeol ordered officials to take swift unspecified steps to get North Korea to face consequences for its provocation. He said he would consider the North Korean missile’s landing near the border “a virtual violation of (our) territorial waters”.

Japanese Defence Minister Yasukazu Hamada also addressed the missiles fired by the North, telling reporters that at least two of them showed possible on “irregular” trajectory. This suggests the missiles are the North’s highly manoeuvrable, nuclear-capable KN-23 missile, which was modelled on Russia’s Iskander missile.

While Prime Minister Fumio Kishida called North Korea’s continuing missile tests “absolutely impermissible”.

Earlier on Wednesday, the South’s Joint Chiefs of Staff said North Korea fired the missiles from its eastern coastal area of Wonsan.

According to a statement, one of the missiles landed in the international waters 16 miles south of the Koreas’ eastern sea border and 104 miles north-west of South Korea’s Ulleung island.

The Joint Chiefs of Staff said South Korea will not tolerate North Korean provocations and will sternly deal with them in close coordination with the United States. It said South Korea has boosted its surveillance posture on North Korea.

Animosities on the Korean Peninsula have been running high in recent months, with North Korea testing a string of nuclear-capable missiles and adopting a law authorising the pre-emptive use of its nuclear weapons in a broad range of situations. Some experts still doubt North Korea could use nuclear weapons first in the face of US and South Korean forces.

North Korea has argued its recent weapons tests were meant to issue a warning to Washington and Seoul over their series of joint military drills that it views as an invasion rehearsal, including this week’s exercises involving about 240 warplanes.

In a statement released early on Wednesday, Pak Jong Chon, a secretary of the ruling Workers’ Party who is considered a close confidant of leader Kim Jong Un, called the so-called Vigilant Storm air force drills “aggressive and provocative”.

Mr Pak also accused the Pentagon of formulating a North Korean regime collapse as a major policy objective in an apparent reference to the Pentagon’s recently released National Defence Strategy report. The report stated any nuclear attack by North Korea against the United States or its allies and partners “will result in the end of that regime”.

He slammed South Korean military leaders over what he called “rubbish” comments that threatened to destroy North Korea if it uses nuclear weapons.

South Korea’s military has warned North Korea that using its nuclear weapons would put it on a “path of self-destruction”.

“If the US and South Korea attempt to use armed forces against (North Korea) without any fear, the special means of the (North’s) armed forces will carry out their strategic mission without delay,” Mr Pak said, in an apparent reference to his country’s nuclear weapons.

“The US and South Korea will have to face a terrible case and pay the most horrible price in history,” he said.