The Unites States previous & current administrations have been misjudging the situation in Syria for almost a decade - with the consequences being more & more visible in recent years, especially since the focus was shifted on the region when the refugees started to move West ....
 

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The role of the Turkish side is kind of 'shadowy' - nobody really knows what Erduan is up to. In addition the U.S.A. is now quite surprised to see China enter the conflict. Elite troops, just like Moscow sent in:
 

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At the beginning of 2016 the situation in Syria has a potential to either lead to a world-wide alliance against terror - or blow this planet apart in World War III.

" .. such a reminder of wrongs committed by our nation got little hearing and was soon overshadowed by an accelerated “war on terrorism” .. Virtually all parts of the world have been the target of U.S. intervention. .. Generally speaking, the much smaller number of Americans who have died is not included in this study, not because they are not important, but because this report focuses on the impact of U.S. actions on its adversaries .. "

To be honest:
I had a vague idea about these facts - but I was really stunned to read this compilation of sorrow, anger, death caused all around the world. In my eyes there's no excuse, no reason can be named why this might be 'justifiable'.

Read for yourselves => LINK

I guess there aren't many people who know about the facts as there is no interest to let them know via mainstream media: willful ignorance.

It might be a reason to think different & change the views about their 'great nation'.