North Korea didn’t celebrate Kim Il-sung’s birthday with a nuclear test, although there was never much indication that it would now, and the regime seemed to downplay it. Instead, North Korea soaked up the attention to show the world that it’s making strides in its missile technology.

Which is just as bad—if not worse.

Specifically, during the annual Day of the Sun military parade, North Korea showed off new solid-fuel rocket technology for its medium- and longer-range missiles, which if Pyongyang can perfect, would significantly shorten its rockets’ launch time. This would make the North Korean military more capable of fighting a nuclear war, while sharply increasing the risk of a conflict.

North Korea relies on fully- or partially-liquid fueled systems for its longest-range weapons, such as the Taepodong, Masudan and Rodong rockets. Liquid fuel has advantages and…