Then you don't know America at all.
America is not defined by its domestic or foreign policies set by fallible men, but its PRINCIPLES. That is such elementary learning that only a foreign would be excused for his/her ignorance.
America would be a bad country - if - its principles found in the Declaration of Independence, it's Constitution, and Bill of Rights laud the white man as superior over all, that its mission is to civilize the world after its image, and it has a right above all others to live so as to be assured dominance, but that's not what its written there.
The principles written in those three documents is what makes America great; it is those that our servicemen have fought so hard for, sacrificed and died so that we will all live free of tyranny.
What it does say is that all men are created equally before God, that no ruler is allowed to set laws without the consent of the governed, and that our rights are inalienable. That its citizenry has the rights among the many to overthrow governments if the same refuses to hear and redress grievances.
Yes, this country's people has made a lot of mistakes in policy, including many unjust wars fought, but those are the people... and NOT the principles the flag stands for.
So if all you know of America is the evil that it committed in the past and present, then you don't know America at all.