Coming out of Vietnam also was the "Powell Doctrine," concocted by that guy holding up the vial of scary anthrax (not) at the UN before Operation Iraqi Fiasco.
The Powell Doctrine (a title made up by others) states that a list of questions all have to be answered affirmatively before military action is taken by the United States:
Is a vital national security interest threatened?
Do we have a clear attainable objective?
Have the risks and costs been fully and frankly analyzed?
Have all other non-violent policy means been fully exhausted?
Is there a plausible exit strategy to avoid endless entanglement?
Have the consequences of our action been fully considered?
Is the action supported by the American people?
Do we have genuine broad international support?
Obviously the US learned nothing from Vietnam, which killed millions of Vietnamese and 58,000 US troops, and injured millions more, both physically and mentally. And yet the US did it again, and again. How stupid. But hey, look on the bright side -- it made a lot of millionaires.
And then 25 months later, Tuesday, April 29, 1975, the iconic "last last helicopter from Saigon" -- photo here
-- but it was NOT the last helicopter and it was NOT from the embassy roof as commonly believed.