This world would be in a far different place without the United States doing what it has done. Germany would have taken over all of Western Europe in WW II without our intervention. After WW II the Red machine would have continued to roll westward without the US staying in place. In the first Gulf war conflict had the US not gotten involved Saddam would have rolled south into Saudi Arabia taking over a very large quantity of the world's oil supply. It is unequivocally clear that in the 20th century that people with an ideology well far of center brought more misery, death and unimaginable suffering than the world had ever seen before. Joeseph Stalin, Mao Zedong, Polpot, Adolf Hitler leader of the German Socialist Workers Party, Castro and others did all of this.... Let there be no mistake in this. It was the United States that stood in the way of or fought against these men of evil, tranny, and unfettered lust for murder of those who were either the "wrong" people or were opposed to their views.
Has this nation been perfect?? Of course not. A nation is like an individual person. Our involvement in Vietnam was a blunder for a variety of reasons. The people in Vietnam did not truly want us there, they did not want to fight for themselves, our leadership was terribly inadequate in assessing the circumstances on the ground in that country. In the Afghanistan circumstance against the Soviets we armed the Mujahedeen which were rather radical in their beliefs. This turned out to be a short term victory with long term severe consequences. Little did we know that these "freedom fighters" would turn out to be our worst enemy a little over 10 yrs later. The second Gulf war we did not have a big enough force in place, we did not understand all of the forces in place between all of the warring factions, our forces did not have all that they needed to be safe or do the job well enough and other reasons as well. So, yes while our nation has made some more mistakes in addition to these, one has to realize that our nation has certainly done more good than harm in this world for the past hundred years.
It is through our founding documents that the pathway was laid for the reversal of slavery and Jim Crow laws. It is for this reason amongst many others why our founding documents stand the test of time. The Constitution and Declaration of Independence are a big part of the "genius" that is the United States. It is these documents that have helped shape our nation to become a better place over time. Black men served under the United States flag in the Civil War. The Massachusetts 54th regiment served under a flag and Constitution that was no where near what it should have been at that time. But, these men served with the faith of a mustard seed, a faith that could move mountains, that one day their grandchildren or great grandchildren etc would see a far better day than they were seeing at their time. Little did they know that one day decades ahead in time our nation would elect a man President with a phenotype that was their own, a lady would would be one of the richest in the entire nation, a man who played a game would be one of the most recognizable wealthy men on the face of the planet. The men in the 54th Massachusetts regiment had that faith and belief. The Navajo Indians certainly did suffer during the take over in the western US. However, it is with their service in WW II that helped us defeat the Japanese in the Pacific theater. It was for the same reason as and faith that the Massachusetts 54th regiment men had.... The belief, faith and hope for a better day ahead for their children, grandchildren, great grandchildren etc... Their faith, belief, and hope are mirror images of the first people who rebelled against the King of England. It is the founding documents that can make all these ambitions a possibility to begin with. It was the man, a flawed man at that in Martin Luther King Jr who was able to help articulate how the promise, hope and potential for those founding documents apply to ALL people. This nation is not perfect as no man is, but it is possible through flawed men greatness can flow, that greatness can lead to an unleashing of potential yrs or decades from first penned or thought of. It is that..... That has made this nation a far better place, and has a result the world a better place in general too.