The Taliban has retaken Afghanistan with lightning speed, forcing Americans to grapple with our 20-year-long tragedy in the war-torn Central Asian nation.

U.S. policymakers, military leaders and ordinary citizens have reckoned with such a defeat before, when the United States failed to achieve its political objectives in Vietnam. Indeed, decades later, the loss remains difficult to resolve. It’s easy to overstate the parallels between these two wars, but as the Taliban reemerges as the governing power in Afghanistan, Vietnam teaches that we’re in for an intensive battle over the past, present and future of U.S. foreign policy and military strategy.

The causes of the Vietnam debacle in the 1960s and 1970s were myriad. Top among them: policymakers’ inflated concerns throughout the war about maintaining U.S. credibility. President Lyndon B. Johnson believed the nation’s global standing against communism was at stake when he chose to go to war in Southeast Asia. After the conflict’s end, former national security adviser Henry Kissinger likewise recalled that “nothing less than America’s credibility was at stake” in Vietnam. In reality, the war hardly altered the United States’ global influence, suggesting these fears had been exaggerated.

The realization of a failed war fueled a blame game that began even before combat ended. David Halberstam’s 1972 classic, “The Best and the Brightest,” for example, concluded that “the inability of the Americans to impose their will on Vietnam had been answered in 1968, yet the leadership of this country had not been able to adjust our goals to that failure.”

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