If 911 was 2001 and China started Islands in 2014 i don't see your point. Currently America is capable of multiple conflicts support. 11 yrs of why? 1.Russia vs Ukraine
2. Israel vs half the middle-east.
3. Most recently while the others have and still do exist Venezuela.
Now America has hardly used its naval capacity for Ukraine.
So that leaves middle-east. 1 theatre.
2nd theatre of issue China of which naval capacity has been around the whole time?
3. Recently naval forces to Venezuela.
So your explanation

Don't see it. Continuous freedom of rights through trade route reconnaissance and patrols etc through contested areas from the start.
If the Philippines navy is capable of sierra madre manned with soldiers on a ship wreck of all things. Surely the seventh fleet could have manned the first and second islands at the start as deterrence from more islands.