North Korea claims to have ground-tested a “newly upgraded” solid-propellant rocket motor about 20% extra highly effective than the brand new motor it revealed in September 2025. The supply of the motor’s thrust enhance is unclear, as is whether or not any Russian help was concerned. Pyongyang related the brand new motor with “strategic forces” however not a selected missile system; use as the primary stage of an intercontinental ballistic missile (ICBM) is more than likely. The appearance of the brand new motor additional muddles the outlook for the North’s future stable ICBM pressure, elevating questions as as to if there might be yet one more new system along with the as-yet-untested Hwasong-20 (HS-20) revealed final fall, and whether or not that new system would supplant the HS-20 and even the prior HS-19, which has solely been flown as soon as. For each the brand new motor and its predecessor, the more than likely goal of their elevated thrust can be in boosting heavier payloads; essentially the most strategically impactful such payload can be a number of warheads if the North can efficiently develop them.
Data to Date
North Korean media on March 29 reported that Kim Jong Un had overseen an undated floor (static) take a look at of a “newly upgraded,” “high-thrust,” solid-propellant rocket motor “utilizing the composite carbon fiber materials.” The motor was claimed to have 2,500 kilonewtons (kN) of thrust (about 562,000 lbs). Accompanying images present a composite-case motor (in step with the usage of carbon fiber) that seems roughly the identical diameter as the primary stage motors of the North’s beforehand revealed stable ICBMs, the Hwasong (HS) -18, -19, and -20. It’s unclear how the brand new motor’s size compares to the primary stage of the HS-20, which is assessed to be longer than that of the HS-19, which in flip, might be longer than that of the HS-18.
Pyongyang didn’t ascribe the brand new motor to a selected missile system past saying it was associated to “strategic strike” and “strategic forces.” The article mentioned the take a look at is a part of the brand new five-year plan that “set[s] the regular upgrading of strategic strike means as a significant purpose… each in high quality and amount,” and was characterised by the introduction of “higher elements with superior financial and technical effectiveness” like the brand new motor.
Evaluation and Implications
Motor functionality. If North Korea’s claims are right, the brand new motor has about 20% extra thrust that the 1,960 kN claimed for the HS-20 first stage motor revealed in September 2025, which the North additionally mentioned can be utilized in a brand new variant of the HS-19. (By the use of comparability, the Nineteen Eighties US Peacekeeper stable ICBM’s first stage had 2,200 kN of thrust.) The supply of the claimed thrust enhance is unclear; prospects embrace an extended motor and/or a small diameter enhance, extra energetic stable propellants, and improved motor design. Whether or not any of those modifications are attributable to any Russian technical help is unknown.
Missile system affiliation. The “strategic” missile more than likely to be related to the brand new motor is an ICBM, though use in a brand new intermediate- or medium-range ballistic missile can’t be dominated out. Use in an ICBM-range submarine-launched ballistic missile (SLBM) is unlikely, because the peak constraints of missile subs typically dictate shorter missiles with larger-diameter levels.
The appearance of the brand new motor so quickly after the revealing of the HS-20-associated motor final fall additional muddles the query of the evolution of the North’s stable ICBM pressure. Will the brand new motor go into yet one more new ICBM past the not-yet-tested HS-20 and the just lately introduced (and in addition unflown) HS-19 variant? If the brand new motor is longer than that of the HS-20, will or not it’s mixed with longer higher levels right into a missile in a position to match on the longer, 12-axle road-mobile launcher chassis revealed in September 2024? Will the brand new motor change the one unveiled in September 2024 within the HS-20, or will a brand new ICBM utilizing the brand new motor supplant the HS-20, the HS-19 variant, and even the unique HS-19 (which has solely been flown as soon as in October 2024)? Extra information sooner or later might be wanted to reply these questions.
Navy utility. The usage of sturdy, light-weight carbon-carbon within the motor case (the heaviest a part of the stage past the stable propellant itself) implies that extra of the brand new motor’s thrust can be obtainable to loft bigger payloads or enhance the general missile’s vary. As a result of even the HS-18 is assessed to have the ability to attain targets all through the continental US, elevated vary wouldn’t appear to be a crucial use of the brand new stage’s elevated increase capability. As an alternative, lofting a heavier payload to the identical vary seems to be the most effective use of that elevated capability.
A heavier (and thus larger-yield) single nuclear warhead or the addition of warhead decoys or different missile protection penetration aids are attainable makes use of for elevated payload capability. However essentially the most strategically impactful use can be in lofting the a number of warheads and post-boot automobile (payload “bus”) related to a a number of, independently-targetable reentry automobile (MIRV) payload. The North revealed multiple-warhead missiles as a growth purpose in 2021, and performed what it mentioned was a MIRV payload flight-test in June 2024 (albeit unsuccessfully). If MIRVs can efficiently be developed, probably requiring no less than a number of profitable flight assessments over a minimal of some years, the North may additional complicate the duty of allied missile defenses and enhance the variety of targets that its missile pressure can strike with a given variety of missiles and launchers.
