The North Korean radio station, Radio Pyongyang has broadcasted coded messages on 6400kHz, reports Strategic Sentinel.
According to Strategic Sentinel, the broadcasting of the coded messages by the station usually precedes an upcoming provocation.
It added that similar broadcast happened two days before the 6th nuclear test, one day before first Hwasong-14 intercontinental ballistic missile (ICBM) test and one day before both ballistic missile flyovers over Japan.
Radio Pyongyang has broadcasted coded messages on 6400kHz. Usually when they do this it signals an up coming provocation.
— Strategic Sentinel (@StratSentinel) September 23, 2017