I don’t think China is building the cables to prevent US incursions but to build/be a more “indipendent internet”, without using the *otherworld cables that they cannot have fully under control.
Nations that use technology to enslave people should be cut off from the global internet and trade. The nasty influence these nations exert on free democracies is insidious... See how LeBron James and the NBA support dictators, and even Jamie Dimon kowtow to evil men.