because the entire planet including the North Koreans know where each and every one is at any given moment of the day such as right here
pardon me if I am wrong but to rain fire and fury or shock and awe upon that PHAT PHUCKING PUNK Kim, I would want three carrier groups right there off the coast ready to lauch airstrikes. Yes, the Air Force has planes in ROK, Japan, Okinawa and Guam as well as other places but nothing intimidates more that carriers sitting right there at the ready. Besides, carrier airstrikes come from close range so there is much less warning time to ready antiair radar and missiles.
regarding other naval assets, they have their weapons load to shoot and then have to disengage to go replenish. again, not highly intimidating once you get your defenses up. The whole idea would be to destroy all of those in the opening hours leaving North Korea naked and vulnerable. Don’t you understand tactical warfare at all?