North Korea said Friday it test-fired long-range cruise missiles off its eastern coast a day earlier, adding to a provocative streak in weapons demonstrations as its rivals step up military training.

The launches, which were later confirmed by South Korea’s military, were intended to verify the reliability of the missiles and the rapid-response capabilities of the unit that operates those weapons, North Korean state media said.

The launches took place as the U.S. and South Korea held a simulation in Washington aimed at sharpening their response to North Korean nuclear threats.

Pyongyang’s official Korean Central News Agency said the four missiles flew for nearly three hours after being launched from the northeastern coast, drew oval and figure-eight patterns above the sea, and showed they can hit targets 1,240 miles away.

South Korea’s Joint Chiefs of Staff said the flight details announced by North Korea had discrepancies with the readings by U.S. and South Korean intelligence assets, but it didn’t elaborate. It said the allies were continuing to analyze the launches.

Lee Hyojung, spokesperson of Seoul’s Unification Ministry, which handles inter-Korean affairs, denounced North Korea for escalating its testing activity despite signs of deepening economic isolation and food insecurity.

North Korea first tested a long-range cruise missile system in September 2021 and has implied the missiles are being developed to be armed with nuclear warheads.

It also test-fired an intercontinental ballistic missile Saturday and a pair of short-range missiles Monday to demonstrate a dual ability to conduct nuclear strikes on South Korea and the U.S. mainland.

North Korea said Monday’s short-range launches were a response to the United States flying B-1B bombers to the region for joint training with South Korean and Japanese warplanes on Sunday in a show of force following the North’s ICBM test.

Prior to the ICBM launch, North Korea vowed an “unprecedentedly” strong response over a series of military drills planned by Seoul and Washington. North Korea has described the annual U.S.-South Korea drills as rehearsals for a potential invasion, although the allies say their exercises are defensive in nature.

Cruise missiles are among a growing number of North Korean weapons and are designed to be maneuverable in flight to evade defenses.

Since the collapse of negotiations with the United States in 2019, North Korea has been accelerating its development of short-range solid-fuel ballistic missiles targeting South Korea, including those that travel on low trajectories that theoretically would be harder to intercept.

North Korea is also trying to develop solid-fuel ICBMs, which could be easier to move on vehicles and can be fired faster than the North’s existing liquid-fuel ICBMs, reducing opportunities for opponents to detect the launches and counter them.

North Korea is coming off a record year in weapons demonstrations with more than 70 ballistic missiles fired, including ICBMs with potential to reach the U.S. mainland. It also conducted what it described as simulated nuclear attacks against South Korean and U.S. targets.

Leader Kim Jong Un doubled down on his nuclear push entering 2023, calling for an “exponential increase” in nuclear warheads, mass production of battlefield tactical nuclear weapons targeting “enemy” South Korea and the development of more advanced ICBMs.

US – South Korea Simulation Exercise

The U.S. Department of Defense and South Korea’s Defense Ministry said their militaries conducted a simulation at the Pentagon on Wednesday that was focused on the possibility of North Korea using nuclear weapons. The allies discussed ways to demonstrate their “strong response capabilities and resolve to response appropriately” to any North Korean nuclear use.

The Americans during the meeting highlighted the Biden administration’s 2022 Nuclear Posture Review, which states that any nuclear attack by North Korea against the United States or its allies and partners “will result in the end of that regime,” the U.S. Department of Defense said. It was referring to a legislatively mandated document that spells out U.S. nuclear policy and strategy for the next five to 10 years.

The U.S. and South Korean delegations also visited Naval Submarine Base Kings Bay in Georgia, where they were briefed on the mission of Ohio-class nuclear-powered ballistic missile submarines. U.S. officials at the base described such forces as key means of providing U.S. extended deterrence to allies, referring to a commitment to defend them with the full range of its military capabilities, including nuclear ones.

Senior North Korean Foreign Ministry official Kwon Jong Gun denounced the allies’ simulated exercise and visit to the Georgia submarine base, calling the actions an extension of anti-Pyongyang hostility. Kwon in his statement also complained that the U.N. Security Council held an emergency meeting this week to discuss recent North Korean launches.

During the meeting on Monday, the United States and its allies urged the Security Council to condemn the North’s unlawful ballistic activities, while China and Russia blamed Washington for raising animosity by stepping up its military exercises targeting Pyongyang.

“The U.S. should bear in mind that if it persists in its hostile and provocative practices against the DPRK despite the latter’s repeated protest and warning, it can be regarded as a declaration of war against the DPRK,” Kwon said, using the initials of North Korea’s formal name, the Democratic People’s Republic of Korea.

In face of the North’s growing threats, South Korea has been seeking stronger reassurances from the United States that it would swiftly and decisively use its nuclear capabilities to defend its ally from a North Korean nuclear attack.

“The United States will continue to work with (South Korea) to ensure an effective mix of capabilities, concepts, deployments, exercises, and tailored options to deter and, if necessary, respond to coercion and aggression by (North Korea),” the Department of Defense said in a statement.

Meanwhile, Seoul’s Unification Ministry said it will resume radiation exposure tests for North Korean escapees who had lived near the North’s northern nuclear testing ground since its first detonation in 2006. Previous tests conducted on 40 escapees found nine people with abnormalities that could indicate high exposure, though no direct link to radiation was established.

The Seoul-based Transitional Justice Working Group had urged South Korea to resume such tests, saying radiation may have spread by rainfall and groundwater. The U.S. and South Korean officials have said the North Korea is likely preparing to conduct its seventh test at the site in Punggye-ri, which would be the first since 2017.

Lee, the ministry’s spokesperson, said the government plans to provide tests to any of the 881 people who had lived in that North Korean region after 2006 who wish to be tested.