Last month, after Afghan militants unleashed sophisticated, synchronized attacks across Afghanistan, including in the capital, the Pentagon was quick to emphasize what hadn't happened. "I'm not minimizing the seriousness of this, but this was in no way akin to the Tet Offensive," said Pentagon spokesman George Little.

Defense Secretary Leon Panetta weighed in similarly: "There were no tactical gains here. These are isolated attacks that are done for symbolic purposes, and they have not regained any territory."

This reaction reveals a fundamental misunderstanding of guerrilla warfare in general and of the type waged by the Haqqani network in particular. It's a lesson the United States should have learned decades ago. But more than 40 years after the Vietnam War's Tet Offensive, and after more than a decade of war in Afghanistan, the U.S. military still doesn't get it.

When Vietnamese revolutionary forces launched the 1968 offensive, attacking the South Vietnamese capital of Saigon as well as nearly 150 other sites, they were hoping to spark a general uprising. What they did instead was give the lie to months of U.S. officials' optimistic talk about tremendous strategic gains and a foreseeable victory.

Just months before Tet, Gen. William Westmoreland had claimed there was a successful end in sight. So how were the Viet Cong able to launch such an assault?

In the course of the offensive, some 58,000 revolutionary fighters were killed, and their advance was beaten back. But guerrillas the world over grasped the lesson: In a guerrilla war, it's crucial to highlight your enemy's helplessness to stop you, and it doesn't have to take 58,000 lives to do that.

The Haqqanis lost only 39 in demonstrating conclusively that in war-making terms, they are living in 2012, while the Pentagon is stuck in the mind-set of Saigon, 1968.

Panetta noted that the Haqqani fighters had not taken territory. But that wasn't the point. What territory, after all, could the militants have been out to regain by attacking Kabul's heavily defended diplomatic quarter? The German Embassy? While Panetta granted that the attacks were geared toward symbolic effect, he remained strangely focused on their tactical significance.

As in Vietnam, the U.S. military regularly attempts to prove that it's winning via metrics in Afghanistan. We get reports of enemy captures and body counts, as if the conflict can be won on points, like a boxing match.

In Vietnam, Westmoreland and other top U.S. officials were forever seeking an elusive "crossover point," the moment when their Vietnamese foes would be losing more fighters than they could replace and would have to capitulate. America would win a war of attrition.

But that didn't work in Vietnam, and it's not working in Afghanistan. More than a decade after U.S. forces swept into Kabul, what began as a ragtag, remnant insurgency has grown stronger and continues to vex the most destructively powerful military on the planet. All America's tactical gains and captured territory, especially in the Taliban heartland of southern Afghanistan, haven't brought the country anywhere near victory. America's trillion-dollar military still is incapable of fully securing even a small "green zone" in the heart of the Afghan capital, much less the rest of the country.

The conflict in Afghanistan began with its American commander declaring, "We don't do body counts," but a glance at recent U.S. military press releases touting supposed high-value kills or large insurgent body counts indicates otherwise. As in Vietnam, the United States is betting on a war of attrition.

But the enemy hasn't bought in. Instead of slugging it out toe to toe in large, suicidal offensives, the Haqqanis and their allies have planned a savvy, conservative campaign meant to save fighters and resources while sending an unmistakable message to the Afghan and American people.

The attrition of U.S. support for the war is unmistakable. As late as 2009, according to a poll by ABC News and the Washington Post, 56 percent of Americans believed it was still worth fighting. Now that number has dropped to 35 percent, while the share convinced that the war is not worth fighting has jumped from 41 percent to 60 percent. The latest offensive is likely to reinforce these trends.

Nick Turse is the associate editor of TomDispatch.com. This appeared in the Los Angeles Times.