I guess I don't really understand your concerns of an 'invasion'

This is not how modern warfare is being orchestrated, you can look to the europe to identify the pattern invoked by the groups in play.

When it comes to the chinese, they have a significant body of people already in north america in many important positions. They have now police stations placed sporadically across north america as a simple example.

The only 'invasions' that occur, are where you can show up with enough power and equipment to offset the locals, this is not something anyone can do to a peer / populated country.

Currently they have hypersonic weapons and we have no recourse, so if we pull up on their shores with our boats we will learn about power projection to peer countries. Not something we have ever done.