And it's not just the US, training using highways. Around two dozen countries have been doing this lately, including India, Taiwan, Pakistan, Australia, Finland, Sweden, and Singapore.
It's more than a few countries that see the writing on the wall, and realize that the wheels came off the planetary fiscal/social/mental bus LONG ago, and that war (or at least attacks) could start any moment. Old tech gives everyone 20-45 minutes of "Get the crap out of here" time. New tech, with hypersonic missiles, gives us half that time (or less), depending on how they are launched and from where (still a LOT of container ships hanging around as well as containers on trains IN the country).
This weekend's events could start up enough chaos locally (inside the country) to allow an external threat or two to start something globally on several fronts at once. We couldn't fight a partial ONE front battle with Gen Milley Vanilly in charge, much less a multi-front, gen4 or Gen5 war with state and "private" actors INSIDE the country as well as foreign actors from outside.