AEGIS can handle most of the short-range stuff coming out of PRC and Norklandia, but THAAD...from South Korea, Japan and Guam is needed for some of the longer range missiles.
We need the Philippines to grant basing rights to cover much of the S China Sea for IRBMs.
These defenses up the ante for any Nork or PRC calculation. They can’t just fire a few at isolated targets and expect them to get through. They have to fire dozens or hundreds at all targets at the same time.
They have to opt for existential war out of the gate. A DAUNTING calculation. Especially since US Strategic forces would be the response to that scale of attack. True end-of-THEIR-world calculation.
launched from Vandenburg?