North Korea conducted a test for solid missile fuel on Thursday, a capability which could shorten launch preparation times, making detection more difficult.

Pyongyang’s Korea Central News Agency (KCNA) reported Kim Jong Un directed the test, which focused on a “jet of high-power solid-fuel rocket engine” and missile stage separation.

“The test was aimed to examine the structural safety of the rocket engine newly designed and manufactured by the Korean style and its thrust and estimate the working specifications of heat separation system and other system,” the English version of the KCNA article reads.

The result satisfied “all scientific and