By 1963, in the wake of the Cuban Missile Crisis, Robert McNamara had come to the conclusion that war per se was obsolete, and all that was necessary was to signal to the enemy how high a price you were willing to pay to deter them. McNamara had obviously developed this view during the Crisis, and in that case it served him well -- war was averted, and America's aims were achieved.
The problem is that the USSR was willing to give up Cuban missiles, in exchange for a guarantee of Cuban safety and a withdrawal of US missiles from Turkey. So not only was the sacrifice palatable to Khruschev, but there was something the US could offer that he was interested in. So when the Americans escalated the situation, Khruschev could still rationalize backing down -- Cuba was "protected" and Soviet security was improved by the removal of missiles from Turkey.
The problem with Vietnam was that a) no sacrifice of the North's aim was acceptable to them -- they saw national reunification as a matter of life and death -- and b) there was nothing the US could offer them as reward for compromise (because of A.) In this scenario, escalation had exactly the opposite effect on the North that it had on the USSR: rather than back down, the North escalated in step with the US, even though these escalations were far bloodier for the North than for the US.
Even at the close of the war, Nixon's extensive bombing campaigns only succeeded in bringing the North to agree to formalize the status quo, with Northern units still inside the South when the US left.
Which brings us to Iraq. It's almost too kind to describe this "surge" idea as a strategy, because I think it's clearly a political lifeline that Bush is grasping for to ride out the last of his tenure. Still, the insurgency's motivations aren't exactly mysterious: Yankee Go Home. And they're clearly willing to sacrifice a lot: suicide bombers exist, and have flourished in Iraq. Is there any compromise possible with these actors? No. Is there any incentive the US can give them for desisting? No. So what will an American escalation produce?
You got it -- an Iraqi escalation:
At the same time, the Mahdi Army in Sadr City has begun a conscription drive to expand its ranks. Every family with a male between the ages of 15 and 45 is being forced to relinquish him to the militia.Escalation: designed to fail.