One can write of the decline of the USA, and that has already been noted many times. One can write of the collapse of the USA, and that arguably is in process. But neither characterisation would capture what is now happening to the USA.
The USA is being destroyed before our eyes. The nation with the greatest military defences in history, by far, is being taken over and sacked. Like Singapore in World War II, it’s guns are pointing in the wrong direction. This time the destructive horde is not Japanese soldiers rattling overland on bicycle rims, it is people who claim to be patriotic Americans.