North Korea has unveiled an apparently new solid-fueled intercontinental ballistic missile, photos released by state-run media showed Thursday, as leader Kim Jong Un doubles down on a pledge to build even more advanced missiles and nuclear bombs.

The display of apparent mock-ups of the powerful new missile — which would allow for more stealthy launches — came during a massive military parade marking the 75th anniversary of the North Korean army’s founding late Wednesday in Pyongyang’s Kim Il Sung Square.

The bulk of North Korea’s long-range ballistic missile arsenal consists of weapons that use liquid fuel, which requires them to be fueled up at launch sites — a time-consuming process that leaves them open to pre-emptive strikes. Solid-fueled ICBMs, however, would not need to be fueled up, making them easier to deploy quickly and more difficult to spot and shoot down.