US strategy is to have overwhelming military superioriity over China and Russia that they can feel secure to attack us with impunity but US will likely be first to collapse if enemy can breach in their homeland defense because they will not know how to cope with chaos, death and destruction. Throughout US history, they have never been invaded or massively under enemy bombardment but unlike China and Russia we have lost over millions of lifes during WW2, we know what we will expect if there is a war.
Imagine in the future that technology to get into space will be so cheap, we can weaponized the space and place all kinds of missile just directly over US space, THAAD will never be anymore an issue for China
, US can be checkmate this way too