But McCain has a point -- or at least he would have had a point if he'd mentioned this concern before it had already long been a reality. Americans don't have much of a stomach for pointless, interminable war. We don't have endless patience with "turning the corner" or "light at the end of the tunnel" rhetoric, as bodies pile up.
What turned the public against the Vietnam Conflict was that the aftermath of Tet gave the lie to all the rosy predictions and showed Americans just how long that tunnel could be.
Although US public opinion polls continued to show a majority supporting involvement in the war, this support continued to deteriorate and the nation became increasingly polarized over the war. President Lyndon Johnson saw his popularity fall sharply after the Offensive, and he withdrew as a candidate for re-election in March of 1968. The Tet Offensive is frequently seen as an example of the value of media influence and popular opinion in the pursuit of military objectives. That the Communists were able to mount a major, country-wide assault at all was a blow to U.S. hopes of winning the war rapidly, and starkly called into question General Westmoreland's earlier public reports of progress in the War. Likewise, the optimistic assessments of the Johnson administration and The Pentagon came under heavy criticism and ridicule.
Seeing the complete collapse of the PAVN/Viet Cong offensive, the lopsided casualty ratio, the lack of a popular uprising in support of the attacks, and the failure of the attacking forces to gain and hold significant territorial assets, Westmoreland considered it an appropriate opportunity for a counteroffensive action. He put together a request for 206,000 additional troops to prosecute the war in the wake of the Offensive, a move that would have required mobilization of the U.S. Reserves.
While this was being deliberated, the request was leaked to the press and published across three columns of the Sunday edition of The New York Times on March 10, 1968. Then-Lieutenant Colonel Dave Palmer later wrote in Summons of the Trumpet: "Looked upon erroneously but understandably by readers as a desperate move to avert defeat, news of the request for 206,000 men confirmed the suspicions of many that the result of the Tet Offensive had not been depicted accurately by the President or his spokesmen. If the Communists had suffered such a grievous setback, why would we need to increase our forces by 40 percent?" [emphases mine]
And Lyndon Johnson never even declared "Mission Accomplished" on the deck of an aircraft carrier or anything.