I would not label the Ukraine a defining tragedy. How about 911 and Viet Nam?
Whether you realize it or not our failure in Ukraine is changing the world order and exposing how poorly led and weak we actually are. Russia's GDP is less than half that of California yet they have been able to thumb their nose at all of Western civilization.
By 2030 BRICS countries will control more economic activity than G7. The almighty dollar will be no longer be dominant. This is going to be a far more serious problem for our children and grandchildren than Vietnam or 911. This is what our counter-productive and failed monetary sanctions have accomplished. Russia's economy has actually grown because of them.