People ride on a trolley bus past a North Korean national flag flown to mark the celebration of the Songun Day or the “Military First” holiday in Pyongyang, North Korea, Thursday, August 25, 2016. North Korea marked its “Military First” holiday on Thursday with mass dancing, outdoor concerts and boasts of a successful – and potentially game-changing – submarine-launched ballistic missile test it hopes will serve as a warning to Washington and Seoul to stop holding joint military exercises Pyongyang sees as a dress rehearsal for invasion.