The U.S. And China's Invasion of the Pacific?

If china were to move against you, and i'm sure seeing them, their incursions into your air space and around your seas, the straits, there is uncomfortable. The united states, as i understand it, are not committed to defending tian and japan is the other big in the region. What guarantees would you have in the event that ch China decided to make its move? I i think the guarantee will definitely, which i think it's almost impossible for the united states to make publicly,. But there's so much unpredictable elements in that ho you know, like level of whether the us. Can really make such a promise; how far will the so called regional alliance go