Yeah. Now as Danish I am both a vassal of the USA and benefit from being a vassal, if I may phrase it in historical terms.
So I am both angry at you and like you. Now since I try to be realistic about that as a European in the Western part, I benefit more from the good parts of USA's politics, yet I am aware of the bad parts.
I believe that the US government's official position is that we have no vassals. I don't think anyone in our government would ever publicly acknowledge or admit that Denmark or any other officially independent nation is a vassal. Americans view Denmark as a free and democratic society, where its government operates as a sovereign entity under a mandate from its people. If they wanted to, they could withdraw from NATO tomorrow, or any other alliance, treaty, or agreement, and there's absolutely nothing the U.S. or any other country could legally do about it. (By "legally," I mean within the precepts of the UN Charter and what is commonly recognized as "international law.")
I understand what you're saying, at least in terms of the practical reality which nations have to face, but one thing I keep in mind is that our own government tends to look at things from a strictly legalistic point of view. They can't help themselves; most of those running things are lawyers.
Also, US foreign policies and our geopolitical perceptions have been largely Euro-centric throughout our history. When we got started, the main focus was in how to stay independent and keep from falling under the thumb of another power. While we were separate from Europe, we still came from Europe and understood how their nations and national governments operated, so we opted to remain diplomatically neutral when it came to Europe. We didn't have any vassals, as we were far more worried about becoming vassals ourselves. That idea remained at the core of US foreign policy.
That started to change in the decades following the Civil War and leading up to World War I, although that was a period when national unity and patriotism for America was a very strong sentiment, and this formed the basis for how many Americans still see themselves and America today. At the same time, on a more practical level, the European dominated, colonialist world order also seemed to mesh well with US interests. This was particularly true in regards to the British, with whom Americans often cite our special relationship. That really became our main connection and conduit into European politics. We were no longer their vassal, but they never became our vassal either. Our history was far too intertwined and interconnected that we could ever really have that kind of relationship. But we did have a number of common interests, and as sea powers, freedom of the seas is a concept that both of us knew intimately well. Our homelands were situated in such a way that, if anyone wanted to attack or invade us, they would have to cross the water, and therein was our advantage. With a friendly neighbor to the north and US hegemony to the south - and two oceans on the east and west - we were pretty safe from such far-off powers as Germany or Russia.
But a lot of that also depended on the stability of the British Empire and their ability to maintain it. The French also had an empire, and so did the Dutch, Belgians, Germans, and even the Danish at one point. I recall that the US acquired the Virgin Islands by purchasing them from Denmark back in 1917.
My point in all of this is to say that, at least originally, the US was neither predisposed nor capable of imposing any hegemony beyond that of a regional power, and as such, we had no real stake in rocking the boat at that point. My view is that European problems emanated from within Europe. We, as Americans, did not cause them, nor does it appear we had any intention or compelling reason to cause any problems within Europe of the kind that led to the World Wars.
And the only reason they were in that situation was because they couldn't handle the Germans. Think of it, the two largest empires in the world, Britain and France, were getting bogged down and fought to a stalemate by Germany. Of course, Germany was a powerful industrial state as well with a certain militaristic philosophy, so they're tough and resilient.
So, if you're a vassal of the USA now, it's only because the British and French just couldn't cut the mustard when it came to dealing with Germany. If not for that, then you'd likely be a vassal of Germany or Russia.