A conscientious objector unearths the lessons of the 'American War'

However, though the crimes of the Khmer Rouge are not taught in Cambodian schools, the country does memorialize the Pol Pot reign of terror by preserving at least one of the killing fields as an open-air museum of atrocity. A primitive marker identifies a tree against which children were bludgeoned, and another stands above a pit that serves as the mass grave for 450 victims. Piles of parched skulls gaze at visitors, pleading for remembrance. A few miles away stands S21, a former high school converted into a detention center where thousands of Cambodians were interrogated and tortured. The Khmer Rouge meticulously documented their savagery, and, in addition to their implements of abuse, a photographic record of their victims is on display at S21. Despite — or because of — their crudeness, the Killing Fields and S21 together are at least as disturbing as more polished curations of cruelty that I have visited: Yad Vashem in Jerusalem; Wounded Knee, South Dakota; Lima's Museo de la Inquisición y del Congreso; the Nanjing Massacre Memorial Hall. If Angkor Wat, the majestic Hindu temple complex that was constructed in a forest outside Siem Reap early in the 12th century, is an enduring monument to human invention and ambition, the Killing Fields and S21, located just 250 miles south, are a reminder of the barbarism to which our species reverted in the final decades of the 20th century.

Why Are We in Vietnam? asked Norman Mailer in the title of a novel published in 1967, weeks before Walter Cronkite, aka "the most trusted man in America," returned from the Asian combat zone to tell his television audience that "it seems now more certain than ever that the bloody experience of Vietnam is to end in a stalemate." It in fact ended in defeat for the United States, when, on April 30, 1975, the last helicopter retrieved a few of the thousands of desperate refugees from atop the U.S. embassy in Saigon. Entering through the muddy Mekong from Cambodia, I was in Vietnam 45 years later because of the outsized role that a distant land less than half the size of Texas has played in my nation's affairs for most of my life.

American forces were in Vietnam in 1967 because of the spurious domino theory, the Cold War fear that if one country in Southeast Asia fell to the Communists, all the others would automatically follow. We were intruding into a civil war, supporting the tyrannical group based in Saigon against the one based in Hanoi. Geopolitics is not dominoes, and the fact that Vietnam, Cambodia, Laos, and China have fought with one another for centuries ought to have led policy makers to conclude that the game was roulette, not dominoes. After chasing out the Americans and, before them, the French, Vietnam went to war against both China and Cambodia. Today, it is nominally Communist, but collective farms have been privatized, and the country's cities are bustling with capitalist enterprise. Yankee imperialists are back, with Burger King, KFC, Pizza Hut, Carl's Jr., and even a place called Texas BBQ. In addition to the huge traditional Ben Thanh Market, posh boutiques proffer pricey European and American merchandise. Vietnam's largest city (about 7.5 million) has been renamed Ho Chi Minh City to honor the man who fought the Japanese occupation with the help of the United States and later led the struggle to evict the French and then the Americans from his country. But most Vietnamese I met still refer to the city by its older, simpler, two-syllable name, confident that, like Leningrad, which reverted to St. Petersburg after the Communists lost control of Russia, Ho Chi Minh City will once again be named Saigon. Nevertheless, despite its embrace of the free market, the Socialist Republic of Vietnam, a one-party state, is neither a democracy nor a champion of human rights. Several dissidents defended as "prisoners of conscience" by Amnesty International sit in prison in Vietnam.