Because the United States has a strategy that relies on deterrence. That's what's stopping them today, and maintaining that advantage is a critical component of scaring China away from arbitrary harassment campaigns like they engage with in the Philippines.

You need to stop reading into sensationalist headlines and actually understand the strategies at-play here. This is about creating sufficient conditions for China to not invade Taiwan, not blowing each other up in a second floating Ukraine. China doesn't want that, Taiwan doesn't want that, and the United States doesn't want that either. The critical difference between posturing and realpolitik is actually doing something; China will refuse to commit to a violent invasion unless globalism fails them (hint: globalism never fails China).