We often underestimate it though. The cold war funneled the very brightest of our men into building the most robust, prepared homeland war that's ever existed. Those preps didn't just disappear, we're using them to this day, shipping artillery rounds from 1960's aid abroad to blow up russians.
The rot has seeped into our bones, but we still have an amazing, awe-inspiring number of them. There are too many variables at play to really give it to china/russia in a battle. They would have to strike hard and fast, and break our political will without inflaming a bunch of us to join the fight. Doable, yeah, but not guaranteed.
Our big chinks right now are our lack of heavy sealift capability, which hampers our mobility in projecting land power abroad. Our dependence on foreign ports in the pacific, possibly, and our unpreparedness for an all-drone war stand out against the chinese. Against russia it's the difficulty in moving the army over there quickly, and keeping us mobile without heavily relying on the air force to ship everything overnight as attrition sets in. Then a prolonged conflict would add a lot of wildcards, as untested, next gen wunderwaffe gets pushed to the limits of readiness against a tech sophisticated foe.
It's very interesting to chew on, a thousand variables. Most of all: Luck. You never know when the die comes up with a 6 on your enemy's turn