Since PRC represents "Chinese" territory at UN, one is illegal trespassing, other is self defense. US physically inserting itself in PRC territory during a lega

Since PRC represents "Chinese" territory at UN, one is illegal trespassing, other is self defense. US physically inserting itself in PRC territory during a legally ongoing civil war and eventually getting slapped is perfectly "legal", whether legality matters in international law when great powers interest clash is another matter.