One of the most obvious portents in which you can see the fall of an empire is when they stop trusting their military advisors, and begin replacing them en masse with yes-men and other useless wastes of flesh.
You cannot possibly obtain accurate assessments from civil or military servants who know that the instant they deliver bad news, they'll be shitcanned. There just aren't enough good folks willing or able to risk their positions. What you're going to get are a set of data which align with the boss' preconceived notions, and as it so transpires, reality doesn't care what premonitions Trump sees in his daily shit.
The US military is cooked. Hegseth has fucked it harder than one of Vance's couches, and there's no end to the damage that has to be repaired, if indeed it can be.