I believe this is as much for North Korea’s ears as their own people’s ear.
The meeting is saying a couple of things such as there is no rift between America and Japan, it is also saying that they are taking the possibility of renewed warfare serious.
In other words, Trump is showing his cards and is calling Rocket man’s bluff. The same bluff he has used to get billions of dollars in the past.
I have regarded the talk of evacuation as an important marker to tell if the commitment to military action is for real.