The USA was never intended to be an empire, there's exponentially more defensive capability in the USA than offensive. The people aren't interested in fighting overseas when we feel secure at home in the mainland.
So they weren't interested in going to Vietnam, Persian Gulf, Iraq and Afghanistan. Those wars were mostly supported by American people, especially Iraq after 9.11. In the last century the USA has not actually defended their homeland at all, but spent years fighting abroad.
That's precisely my point.
America isn't designed to conquer other nations, America was designed only to defend against invasion. If Vietnam were supported by "most" American people, there wouldn't have been a draft, or mass civil disobedience, or people choosing potential imprisonment rather than conscription. Vietnam was truly supported by a minuscule minority of Americans, even the soldiers forced to be there felt abandoned by America, and it led to rampant suicide. It's just another example of government officials acting in self-interest against the will of the American people.
The Persian Gulf was recognized as a decisive victory, and yet again it was fought by only 425,000 American personnel, and it didn't have the motivation of the American people behind it either. The American people have been caught in a transition from trusting government into distrusting government. People were more trusting back in the early 90's compared with today...
Iraq and Afghanistan are also examples of extremely limited public support in real terms. The American people overwhelmingly supported a war against Al Qaeda in Afghanistan, but had no interest in going to war with Iraq. The American public en mass also recognizes measured responses, human rights with regard to the use of lethal force, and logic. There was no great need to rally the war effort within society against Al Qaeda because ample capability was already present within the US military to win against Al Qaeda. The will of the public isn't what you hear on the TV, it's the mentality of the people within society; the actions and interactions of mass numbers of individuals.
You'll know it if the American public ever truly supports a war when the number of Americans insisting on fighting outpaces the tactical capabilities of the US military to supply them all to the battlefield. When they start acting individually and independently of the military towards accomplishing those ends, even paying their own expenses to fight. That's the only time when America has the power to assert massive force, when it's obviously necessary for protection or defense.
World War 2 threatened the substance of what was America, in the eyes of most Americans, the consequences of losing World War 2 would've been worse than death, or enslavement. It was the thought of genocide, the extinction of the American philosophy that drove the effort. That's the essence of America. When the American people decide to make a movement, the government can only watch it unfold and assist with logistics. Whenever a cause is great enough that the American people mobilize themselves, the government is below powerless to resist it, any government resistance becomes irrelevant (not to mention hazardous to the officials posing the resistance). America is very different from the rest of the world in this regard, we often fail to recognize the cultural differences between societies. This is one of the cultural differences that separates Americans from the rest of the world.
Americans are still alive in America, and while America has enemies on the inside, we understand never to draw first blood. It's not the American way to abandon diplomacy before the lines are drawn. These wars aren't what America wants, and the powers responsible for perpetuating them are acting in desperation. America is weak without the motivation of its people, and unbelievably strong when the need arises.
The American system creates a massive inclination towards the defensive capability of the people. The American forces available to be used for aggression are insignificant and pale in comparison with the American forces who refuse to fight for the wrong reasons.
I'm not at all saying that America is better than anywhere else, it's got major issues popping up. I'm simply saying that the true strength of America hasn't been seen since the close of World War 2, and it'll never be summoned for transient causes, or for drawing first blood. That's not to say it can never be tricked, but it's only getting more and more difficult for TPTB as time goes on...