In 2019, NASA attempted to demonstrate the transfer of cryogenic propellants at the International Space Station, but the chilling system failed and the liquid methane “boiled off”—turned to gas and was vented into space.

Source: https://qz.com/emails/space-business/1850514330/space-business-cold-storage

It’s not the only technology Kim wishes to develop–also on the cards are hypersonic missiles, intercontinental ballistic missiles (ICBMs) fueled with solid propellants and and nuclear-powered submarines.

Source: https://time.com/6283280/north-korea-military-satellite-launch/

The Hwasong-15 is one of the North’s three ICBMs, which all use liquid propellants that require pre-launch injections.

Source: https://businessmirror.com.ph/2023/03/16/north-korea-launches-icbm-before-south-korea-japan-summit/

The launch must take place from Kennedy Space Center’s Launch Complex 39A, which is the only SpaceX pad at Cape Canaveral equipped to fuel the lander with liquid oxygen and methane propellants shortly before launch.

Source: https://spacenews.com/peregrine-lunar-lander-ready-for-january-launch/