Military analyst Koizumi Yu of the Research Center for Advanced Science and Technology at the University of Tokyo says photos carried by North Korean state media show a hypersonic missile that was test-fired last month.
Koizumi identified the weapon with an orange line on its tip as a hypersonic missile that appears to use as its booster a Hwasong-12 -- an intermediate-range ballistic missile of the same type as one the North fired in 2017.
He estimates its range at around 5,000 kilometers, and says its targets appear to include Guam.
Koizumi points out that the missile has fins that serve as rudders, so it can change course during a relatively long flight through the atmosphere.
He says the weapon displayed alongside other submarine-launched ballistic missiles is likely to be a new-type SLBM that's smaller and has just enough range to reach South Korea.
He says the new missile does not require large submarines, and could be carried by refurbished existing ones.
Koizumi says the North will test-fire the new missile at some point as it steadily modernizes its military capability.