North Korea fired multiple ballistic missiles on Thursday, authorities in South Korea and Japan said, after an unprecedented number of launches on Wednesday.

One of the missiles prompted evacuations in the Miyagi, Yamagata and Niigata prefectures of Japan.

"North Korea's repeated missile launches are an outrage and absolutely cannot be forgiven," Japanese Prime Minister Fumio Kishida said.

He added that one of the rockets may have been an intercontinental ballistic missile (ICBM).

South Korea's Yonhap news agency reported the North Korean missile had potentially failed to continue on its trajectory after initial flight, citing anonymous military sources.

Pyongyang has ramped up such missile tests in recent months, often saying it is a response to the United States and South Korea resuming joint military exercises in the region. It calls the drills a rehearsal for an invasion.

After the additional tests Thursday, the US and South Korean air forces agreed to extend aerial drills. The US State Department spokesman Ned Price said the US was prepared to impose "additional costs and consequences" if Pyongyang conducts a seventh nuclear test.

Japan on alert

Japan's J-Alert emergency broadcasting system initially said one of the missiles flew over the country before landing in the ocean. Tokyo later said this was incorrect.

"We detected a launch that showed the potential to fly over Japan and therefore triggered the J-Alert, but after checking the flight we confirmed that it had not passed over Japan," Japanese Defense Minister Yasukazu Hamada later said.

Yoji Koda, a retired vice admiral and a former fleet commander of Japan's Maritime Self-Defense Forces, Koda told Reuters, "It means at some point in the flight path there was some problem for the missile and it actually came apart."

He added though even though the warhead came down into the sea between the Korean Peninsula and Japan, debris could have continued on its trajectory over Japan given the speed at which it was traveling.

In a phone call on Thursday, officials from Seoul and Washington jointly condemned last launch as "deplorable" and "immoral."

North Korea fires most missiles in a single day

North Korea's launch of 23 missiles on Wednesday was "effectively a territorial invasion," South Korean President Yoon Suk-yeol said. It was the most missiles fired by the North in a single day.

The tests included seven short-range ballistic missiles and six ground-to-air missiles.

South Korea responded by launching three ground-to-air missiles of its own.

One of the North Korean missiles crossed the maritime border between the two countries, landing just 57 kilometers (35 miles) off the eastern coast of South Korea. The incident triggered air raid sirens on the island of Ulleung and forced people to take shelter.

World condemns record day of tests

The United States called the launches "reckless" and said it would make sure it had the military capabilities in place to defend its treaty allies South Korea and Japan.

US Ambassador to the United Nations Linda Thomas-Greenfield said the launches were "unprecedented in the sense that there were so many."

A spokesperson for the US National Security Council, Adrienne Watson, said that US President Joe Biden and his national security team remain in close contact with allies and partners to evaluate the security situation after Pyongyang's tests. Watson noted North Korea was in "flagrant violation of multiple UN Security Council resolutions."

North Korea's actions "needlessly raises tensions and risks destabilizing the security situation in the region," she said.

A spokesperson for the European Union's foreign policy chief Josep Borrell called the latest round of missile launches "a wanton and dangerous escalation," while the United Kingdom also condemned the "unprecedented number of missiles." Russia also called for calm.

What do North Korea's tests portend?

Analysts point to the large joint US-South Korean combined air exercises as being particularly upsetting if not disastrous for Pyongyang given the use of the F-35 aircraft. 

Described by experts as game changing, the Lockheed Martin aircraft places North Korea's anti-aircraft and missile defense systems at risk, as the F-35 is capable of carrying out high-precision strikes with accuracy as well as providing significant visibility on those systems.

Mason Richey, a professor in Seoul at Hankuk University of Foreign Studies, told Reuters that North Korea "really does not like" that the exercises "employ F-35s that can be used for decapitation strikes against the regime and are very difficult for North Korean air defenses to pick up."

Adam Mount, the director of the Defense Posture Project at the Federation of American Scientists, tweeted that the drills were more tactical than strategic, and added the "exercises show what the opening hours of a high intensity peninsular war could look like: large-scale allied air operations and simultaneous salvos from multiple DPRK missile and artillery systems." 

North Korea supplying Russia with weapons — US

Meanwhile, the United States on Wednesday said it had information indicating that North Korea was covertly supplying Russia with a "significant" number of artillery shells for its invasion of Ukraine.

"Our indications are that the DPRK is covertly supplying and we are going to monitor to see whether the shipments are received," White House National Security spokesperson John Kirby said, using the official acronym for North Korea.

In September, Pyongyang said it had never supplied weapons or ammunition to Russia and had no plans to do so.

North Korean leaders also told the United States to "keep its mouth shut" and stop spreading rumors aimed at "tarnishing" the country's image.

ar, zc/nm, msh (AFP, Reuters, AP)