We have always been at war with

[Fill in country of your choice]. It's because we are the bestest superpower in the world that we must force other countries to see our awesomeness.

Arthur Silber explains it more intelligently:

I want to emphasize that this mythology about America is one that, in its central components, arises out of a perspective based on endless, violent conflict: in this sense, we see our country and ourselves as being eternally and perpetually at war. This is a matter of considerable consequence. Given events of the last several years, we can see that it is not at all inaccurate to observe that when wars which are necessary for our self-defense do not manifest themselves, we must invent them. In large part, this explains why Americans acquiesced in our criminal invasion and occupation of Iraq -- and why there is now no massive public demand that we end it immediately. In terms of our mythology, we see ourselves as always being at war, with peoples and countries that are always our inferiors. In this manner, we ensure that what we perceive as an "existential" threat to our nation's continued survival is always present. And so we very frequently are at war (and if not war conducted openly, we engage in an endless series of covert interventions).

He then discusses the horrific history of our behavior in foreign countries and goes on:

Most Americans know nothing of this history. Large-scale public ignorance is necessary to the perpetuation of a fundamentally false national mythology. Today, more than one hundred years later, all of this is repeated again, in precisely the same form. An honest observer knows that we learn only of some of the worst atrocities committed by U.S. troops in Iraq, those that cannot be denied or covered up. There are countless acts of barbarism about which we will never learn anything. And even when we cannot deny the occurrence of monstrous acts, we minimize and "explain" them using identical, contemptibly dishonest mechanisms.

Our mythology is crucially tied to our conception of our self-worth. For most of us, it is life itself. Dispense with the lies and death ensues, at least that is how many Americans experience it psychologically. I think only a monumental shock to these illusions -- in the form of a major economic collapse, a conflict of horrifying devastation, or by some other means -- will ever pry most Americans from these dangerous and destructive fables to which they cling with increasing desperation. In the meantime, the death and destruction will go on, exactly as they have before -- and most of us will do precious little to try to stop them.

We have always been at war ... with the world.