This past Sept. 11, three months before he shot up a Florida naval base, Saudi airman Mohammed Alshamrani posted a cryptic but chilling message on the internet: “The countdown has started.” ABC News reports the post was detailed in an investigative report about the gunman who killed three at Naval Air Station Pensacola before he was shot dead in a gunfight with police. There’s no explanation about the meaning of the message, but as The Daily Beast has reported, Alshamrani also visited the 9/11 Memorial and Museum during a trip to New York City days before the mass shooting. The FBI has said they are treating the shooting like terrorism but have not nailed down the motive.