The only plausible interpretation of "think hack" is that the launch codes were somehow acquired and a bogus action order was transmitted.
But even then… what USN sub crew sitting off the coast of Washington state wouldn't think there was something odd about receiving a launch order to fire a missile at some spot in the ocean while POTUS is in the middle of a major diplomatic summit?
I'm still not able to piece together a coherent story about how this happened.