Southern parts of Boston not being invaded; it just sounds like it

Our military expenditures are not four times those of our neighbor to the north, they are over thirty times. They are also about twelve times those of Russia, the only country that is a threat to the Baltic republics. We could shrink that a lot and still be able to defend them, even without assistance from our NATO allies, three of whom have expenditures close to those of Russia. Of course, Russia has its own strengths, such as its own criminal empire, and the support of the US Republican Party. Our military can't help much against those.

If by Bizarro China you mean Taiwan, I certainly agree that the subjugation of Taiwan by the PRC would be a catastrophe and a tragedy. I spent four years of my childhood in Taiwan, and the idea of that wonderful, not-bizzare place falling under the rule of the brutal, stupid, and corrupt Chinese Communist Party is monstrous to me. Nevertheless I don't think that massive military expenditures by the USA are the primary thing preventing an invasion. The People's Liberation Army is enormous, wealthy, and powerful, but it does not have a history of recklessness; it hasn't engaged in any serious conflicts since it fought a low-level war against Vietnam in the '80s (unless you count the Tianamen Square massacres). China prefers to use the threat of its military to impose its will, without actually using it.

I said that the CCP is stupid, but it now has a large client base of wealthy capitalists who are capable of counting the cost of such an invasion, which would be enormous even if no one came to the aid of Taiwan. The greatest danger that I see is a power struggle in which the leaders of the PLA attempt to maintain preeminence by pushing the country into a military adventure. I don't think our military expenditures would enter very much into their calculations in such a case.