This is how it happened in Vietnam.
Kissenger negotiated a treaty so vague that it looked like a victory to the US and to permission to annex the South to North Vietnam.
South Vietnam's government was supposed to be strong enough to stand on its own. This might have been true, but the officials of the South Vietnamese government chose to take the money and run, and their government collapsed. President Thieu's plane was so loaded with gold and other valuable goodies than it barely cleared the runway.
Our "democratic" allies turned out to be an assortment of corrupt thieves.
Congress then withdrew funds to keep US gtroops in Vietnem. Being as there was not supposed to be a sudden takeover by the North, there was no provision for the speedy withdrawal.
What followed could not be described even by Juniorbush, Cheney or Karl Rove as a victory.
Vietnam, of course, had absolutely nothing the US really needed. The only reason to be there was hubris about how "these colors never run", and the myth that the US had never lost a war.
Ransoms were paid to the Bey of Algiers, the Canadians and Brits burned Washington, including the White House, in the War of 1812, Pancho Villa raided Columbus NM and got away with impunity, and the expeditionary force to Russia was a fiasco, but we chose to ignore those as minor and didn't count them.
Vietnam was a disaster. The blame lies with John Foster Dulles and his equally evil brother Allen who got the US involved in propping up French colonialism in the first place. Naturally, there are many ratwingers who blaqme the Democrats for not allowing them to nuke SE Asia, as though the reprecussions would not havre been far worse. The US using the Bomb would have meant that the Chinese also had an equal right to use their bomb.
It would be nice if greater sanity goes into the withdrawal from Iraq, but I have zero confidence in that hateful, ancient old hack and prize oil company asshole, James Baker. His competence still has yet to manifest itselff in any way anfd the old bastard is damn near 80. I can almost hear Kissinger panting and pawing the turf to get involved in another 'Peace with Honor' scheme.
We need intelligent diplomats and we are stuck with Israeli shill Negroponte and clowns like Baker and Kissinger. Woe is we!