North Korea said Sunday that it had fired off an intercontinental ballistic missile (ICBM) a day earlier, in what Pyongyang called a “sudden launching drill” that demonstrated “actual proof” of the country’s “fatal nuclear counterattack” capabilities.

The Japanese Defense Ministry said Saturday that its reclusive neighbor had launched one of its most powerful long-range missiles into waters some 200 kilometers off Hokkaido’s Oshima Island, inside Japan’s exclusive economic zone (EEZ).

The launch of what Pyongyang said was a Hwasong-15 ICBM came just days ahead of joint military drills between the U.S. and South Korea set for later this week at the Pentagon.

“The surprise ICBM launching drill ... (is) clear proof of the sure reliability of our powerful physical nuclear deterrent,” the state-run Korean Central News Agency said in a report.

KCNA emphasized the drill had been “suddenly organized without previous notice" under an emergency standby order given at dawn on Saturday and a written order by leader Kim Jong Un at 8 a.m.

This was believed to be the first time that such a drill had been conducted with an ICBM. It was also the first time that North Korea had formally introduced its new Missile General Bureau to the outside world. The bureau is thought to handle missile development, planning, production and procurement, as well as logistics support.

Saturday’s launch was significant in that Kim hoped to deliver a message to his enemies that “his country, too, is conducting its own ‘drills’ and exercises to sharpen its wartime reflexes,” said Soo Kim, policy practice area lead at consultancy LMI and a former North Korea analyst at the CIA.

“The regime wants their adversaries to know that the weapons tests — and drills now — are not for mere display, but for actual use,” she added.

Although nine hours had elapsed from Kim’s order to the actual launch around 5:20 p.m., likely due to the time-consuming process of moving, erecting and fueling the missile, analysts said more exercises were likely already being planned to slash that time frame.

“I'd expect the North Koreans to carry out similar drills to bring that time down,” said Ankit Panda, a nuclear policy expert with the Carnegie Endowment for International Peace. “We've seen this type of operational improvement at work with some of their shorter-range systems in the past.”

The KCNA report also confirmed that the launch had been conducted at a high-angle, meaning it had been shot nearly straight up so as to avoid overflying neighboring countries, and was intended to highlight the Hwasong-15’s maximum range. It said the missile had flown 989 kilometers and hit a maximum altitude of 5,768.5 km, while traveling for nearly 67 minutes “before accurately hitting the preset area" in the Sea of Japan.

The North’s First Red Flag Hero Company, the unit that undertook the drill, also conducted the country’s previous ICBM launch in November, according to the report. It said the company had demonstrated “the actual war capacity" of the country's ICBM units.

KCNA said the commission, which is headed by Kim, had also ordered all of his missile units “to thoroughly maintain their strengthened combat readiness” amid tensions with South Korea and the U.S.

In a separate statement published by KCNA, Kim’s influential sister, Kim Yo Jong, vowed that the North would take "very powerful and overwhelming" responses to any hostile acts against Pyongyang.

A composite photo shows a series of bright lights, possibly debris from a North Korean long-range missile, recorded in Hakodate, Hokkaido, at about the same time that the ICBM-class weapon was believed to have fallen Saturday evening. | Courtesy of Goryokaku Station Live Camera / VIA KYODO
A composite photo shows a series of bright lights, possibly debris from a North Korean long-range missile, recorded in Hakodate, Hokkaido, at about the same time that the ICBM-class weapon was believed to have fallen Saturday evening. | Courtesy of Goryokaku Station Live Camera / VIA KYODO

"The U.S. should stop all the actions posing threats to the security of our state and refuse to tarnish the DPRK's dignity, always thinking twice for its own future security," she said, using the acronym for the North’s formal name, the Democratic People's Republic of Korea.

Speaking on the sidelines of a security conference in Munich on Saturday, the top diplomats of Japan, South Korea and the United States condemned the launch, vowing to bolster trilateral cooperation — and urging others to strictly enforce United Nations sanctions on Pyongyang.

“We call on others to condemn this action, to take appropriate steps, including the effective enforcement of sanctions, and countries that have influence with North Korea should use it to try to move it from the course that it’s been on now for the last couple of years,” U.S. Secretary of State Antony Blinken said after a meeting with Japanese Foreign Minister Yoshimasa Hayashi and South Korean Foreign Minister Park Jin.

Pyongyang is banned from using ballistic missile technology under a raft of U.N. sanctions, but China and Russia — both veto-wielding members of the U.N. Security Council — are believed to have taken a more lax stance on sanctions enforcement amid the increasingly acrimonious Sino-U.S. rivalry and Moscow’s war against Ukraine.

On Saturday, Japanese Defense Minister Yasukazu Hamada said that the latest “ICBM-class” weapon was estimated to have a range of over 14,000 km, depending on the weight of the warhead and other factors.

“In this case, that would put the entire United States within its range,” he said.

Saturday's firing was seen as a reaction to the planned joint tabletop military drills between the U.S. and South Korea set for next week in Washington. Those drills are intended to hone the allies' joint response to the potential use of nuclear weapons by North Korea.

Next month, South Korea and the U.S. are also planning to hold annual computer-simulated combined training, as well as joint field exercises that would be bigger than those held in recent years.

On Sunday, the U.S. held joint air exercises bilaterally with Japan and South Korea involving strategic bombers.

The North, which views joint drills between the two allies as a rehearsal for invasion, has vowed an “unprecedentedly” strong response to the exercises.

Tensions over the North’s nuclear and missile programs soared in 2022 as it fired off a record number of weapons in the face of calls by the U.S. and its allies to return to denuclearization talks. Experts say this year could prove to be even more perilous, with signs already emerging that Kim remains determined to follow through on a 2021 pledge to build even more advanced missiles and nuclear bombs.

This, coupled with the U.S., South Korean and Japanese push to bolster deterrence and the decision to ramp-up joint military drills, was likely to turn the Korean Peninsula into a powder keg once again.

“The current dynamics between North Korea and the allies are reasonably described as a spiral, I'd say: Each side is carrying out shows of force while asserting self-defensive rationales, driving the other to respond in kind,” said Panda. “I'd expect matters to deteriorate in the coming months, particularly once the U.S. and South Korea carry out field mobilization exercises.”