Korea and Vietnam were in response to unchecked Communist imperialism and it needed to be stopped. Once the USRR realized that the U.S. would resist every attempt they chilled out on it a little bit.

Iraq and Afghanistan would have never happened without 9/11. 9/11 occurred directly as a result of 8 years of horrible and weak foreign policy under Clinton. OBL should have been taken out in the mid-90s.