US military to defend the borders
This got ridiculous a long time ago. If European countries must rely on the US to defend their borders against Russia, then they are no longer sovereigns in their own right and should be paying us for the privilege of pretending to be sovereign. If the troops paid for with my tax dollars are going to be off protecting Europe, then Europe had better sign a lopsided trade agreement with me to provide a guaranteed market for my goods and low-cost raw materials for me to buy. Of course, the actual threat to the cultures of Europe--unassimilable, r-selected Africans and Middle Easterners--is allowed free ingress.
The world is full of tiny countries that would be reduced to provinces of their larger neighbors without the Pax Americana. Do I as an American really care if Lichtenstein or Luxembourg are independent states? Monaco? Belgium? Three fairly large countries, Syria, Iraq and Libya, have ceased to exist in their previous forms. Has this made any difference in any American's life? Would anybody in the US really care if Ukrainians paid taxes to Russian bureaucrats instead of their hilariously corrupt, incompetent countrymen? Europeans appear no longer to care about their countries as geographic redoubts of their particular ethnic kin, so why should we? Better they be ruled by Orthodox Christian Russians than homegrown Muslim barbarians, which is where all the demographic trends are pointing.
Of course, I've answered my own questions here. This is all, always, about maintaining the status of the dollar as the world reserve currency.