South Korea Warns North Korea Nears Nuclear InterContinental Missile Able to Strike U.S.

South Korea’s president warned that North Korea is close to a nuclear InterContinental Ballistic Missile (ICBM) capable of striking the U.S. mainland. The warning highlights rising risks to American security.

South Korean President Lee Jae-myung confirmed on Thursday, Sept. 25, 2025, that North Korea is nearing completion of an intercontinental ballistic missile designed to carry a nuclear warhead to the United States. While Pyongyang has yet to prove its warheads can survive atmospheric re-entry at hypersonic speeds, Lee warned that the country’s rapid pace of missile development makes the danger increasingly urgent for Washington, Seoul, and Tokyo.
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South Korea Hwasong-19 solid-fuel intercontinental ballistic missile ICBM displayed during its October 2024 test launch, assessed by analysts as capable of striking the entire continental United States if paired with a hardened nuclear warhead. (Picture source: North Korea press agency)

North Korea’s nuclear posture has evolved steadily since its first underground tests. Initially limited to crude fission devices and short-range delivery systems, the regime has invested heavily in both missile development and fissile material production. Today, it possesses a diverse arsenal capable of striking targets from Seoul to Los Angeles. Allied intelligence estimates that North Korea holds dozens of nuclear warheads, with yields ranging from tactical devices of 10 to 20 kilotons to strategic warheads of 100 to 250 kilotons, sufficient to devastate a major city.

At the center of this arsenal is the Hwasong-19, a three-stage solid-fuel ICBM first flight-tested on October 31, 2024. Designed for mobility and survivability, it can be launched quickly from canisterized transporter-erector launchers, reducing the time window for detection and preemption. Analysts estimate its range to exceed 12,000 kilometers, putting the entire continental United States within reach. If equipped with a fully hardened and miniaturized nuclear payload, the Hwasong-19 would give Pyongyang its first truly survivable and operational long-range nuclear strike capability.

The Hwasong-17, a massive liquid-fuel ICBM displayed since 2020, represents another pathway to long-range nuclear delivery. Though slower to prepare for launch, its immense size allows for the potential carriage of very heavy warheads or multiple re-entry vehicles. Its estimated range of 12,000 to 15,000 kilometers also covers the entire U.S. mainland. Experts view the Hwasong-17 as both a political weapon of intimidation and a potential platform for future multi-warhead designs if North Korea masters MIRV technology.

Analysts also speculate about a future heavy ICBM sometimes referred to as the Hwasong-20. Larger payload shrouds and hints of re-entry vehicle testing suggest a long-term ambition to develop penetration aids or even MIRV buses. While no confirmed flight tests have proven these capabilities, even limited use of decoys would dramatically complicate U.S. missile defense.

Alongside its land-based ICBMs, Pyongyang has pursued a survivable second-strike capability through the Pukguksong series of submarine-launched ballistic missiles. The Pukguksong-3, followed by newer variants displayed as Pukguksong-4 and Pukguksong-5, demonstrates ranges of 2,000 to 3,000 kilometers. These weapons threaten Japan, Guam, and U.S. bases across the Pacific. While North Korea’s submarine fleet remains technologically limited, even a small number of SLBM-capable boats would allow the regime to launch from unexpected locations, increasing survivability and complicating allied tracking efforts.

North Korea has also strengthened its theater-level nuclear strike options. The Hwasong-12 intermediate-range missile can reach Guam at approximately 4,500 kilometers, while the KN-23 and KN-24 short-range ballistic missiles provide nuclear delivery capability against South Korea and Japan. Their estimated yields of 10 to 50 kilotons give Pyongyang the option to employ tactical nuclear weapons in a regional war, blurring the line between conventional and nuclear escalation.

All of these delivery systems are supported by a growing stockpile of fissile material. Satellite imagery and intelligence reporting suggest that North Korea operates multiple enrichment and reprocessing facilities, steadily increasing the number of warheads it can field. This combination of quantity and quality shortens the time needed for Pyongyang to overcome its final technical hurdle: reliable re-entry vehicle performance at intercontinental ranges.

The outstanding challenge remains atmospheric re-entry. A nuclear warhead must withstand intense heat and structural stress while maintaining guidance and stability at hypersonic speeds. State media has shown images of new re-entry vehicle shapes, and recent tests have flown lofted trajectories that simulate re-entry, but outside experts have not seen verifiable proof of repeatable success. Once North Korea masters this final step, however, the strategic balance in East Asia will change profoundly.

The main threats posed by North Korea’s nuclear arsenal are threefold. For the United States, the looming possibility of a reliable ICBM force capable of striking Washington, New York, or Los Angeles would alter deterrence calculations and force heavier reliance on missile defense and extended nuclear guarantees. For South Korea and Japan, the immediate threat comes from short- and medium-range nuclear-capable missiles that could strike with little warning and devastate major cities or military bases. For the wider international community, the danger lies in proliferation: a more mature and confident North Korea could export nuclear materials, missile designs, or even warhead technology to other states or non-state actors, destabilizing regions far beyond Northeast Asia.

North Korea’s nuclear program has reached a decisive stage. It already possesses the ability to inflict nuclear destruction on its neighbors and is on the threshold of threatening the U.S. homeland. The combination of expanding fissile stockpiles, mobile solid-fuel ICBMs, submarine-launched missiles, and potential MIRV development represents a layered and increasingly survivable nuclear force. Unless constrained by diplomacy or countered by rapid advances in missile defense and deterrence, Pyongyang’s progress poses one of the most serious threats not only to the security of the United States and its allies but to global stability in the 21st century.

Written by Alain Servaes – Chief Editor, Army Recognition Group
Alain Servaes is a former infantry non-commissioned officer and the founder of Army Recognition. With over 20 years in defense journalism, he provides expert analysis on military equipment, NATO operations, and the global defense industry.