There's no such thing as NATO expansionism. Eastern Europe became dead set on joining NATO after seeing the destruction of Russian democracy by the remnants of the Soviet security-military complex. They correctly predicted that Russia would degenerate into an authoritarian dictatorship that would turn outwardly expansionist after KGB hardliners consolidated power and crushed all internal dissent.

Eastern Europe's entry into NATO is like townsfolk signing up for neighborhood watch after seeing the social order break down in the next town and fearing that criminality will spill over into their own community. The criminals, of course, are disturbed that people are setting up security cameras and looking out for each other. Breaking into houses would be much easier in a town where everyone keeps to themselves.

Eastern Europe managed to break free of Russian military occupation only in 1994. Criminal gangs had taken over our town by force at the end of WWII and prevented us from living normal lives for half a century. Now, the same criminals demand that we dismantle cameras, fire security guards, and stop cooperation amoung ourselves because "neighborhood watch expansionism" violates their "interests." Damn right it does.

I believe showing Russia, China, and the world, that USA stands behinds it commitments and allies, defends the rule based world order and is true leader of the democratic society would deter leaders such as Putin and Xi from trying anything.

NATO is (imo) close to collapsing. All it would take is a minor just-under-war incursion, e.g. in northern Finland by Russia. Would USA (Trump) defend Finland in this scenario? If not, NATO is dead and the next 100 years belong to China and Russia.

Never a better time to throw your allies under the bus.