What does it feel like to push a button, launch a surface-to-air missile, and blow a B-52 bomber out of the sky? Ask Nguyen Van Phiet. As a young North Vietnamese military officer, his SA-2 rockets were credited with downing four of the giant Boeing Stratofortresses during U.S. raids on and around Hanoi in December 1972.

More than 40 years later, sitting in his comfortable Hanoi rowhouse, the wizened, soft-spoken Phiet, 76, a retired lieutenant general and former deputy commander of Vietnam’s air defense force, shows little emotion when recalling those deadly days. “The Americans were disturbing our freedom,” he says in Vietnamese as we sip tea from delicate china cups at his dining room table. “I was fulfilling my responsibility to the nation.”

Among the many weapons in North Vietnam’s anti-aircraft arsenal, few were more feared than the type of missiles Phiet commanded: the Russian-built S-75 Dvina (the SA-2 “Guideline,” in NATO parlance). U.S. combat crews likened the two-stage, 35-foot-long SA-2 to a flying telephone pole. The 5,000-pound missile had an effective range of about 21 miles, streaking toward its target at more than four times the speed of sound, up to an altitude of 90,000 feet to deliver a 430-pound fragmentation warhead that could shred anything within its nearly 300-yard maximum blast radius.

In 1960, an SA-2 brought down Francis Gary Powers’ U-2 reconnaissance aircraft over the Soviet Union. Seven years later, an SA-2 knocked the right wing off of John McCain’s carrier-based A-4 Skyhawk, forcing McCain to eject and parachute, badly injured, into Hanoi’s Trúc Bach Lake, where he was fished from the water and taken prisoner. And it was the SA-2 that delivered what the Vietnamese today regard as their greatest aerial triumph: the destruction of more than a dozen B-52s during the so-called Christmas bombings of 1972. A gleaming museum in Hanoi celebrates the achievement; its name, the B-52 Victory Museum.

Time, vegetation, and urban development have erased virtually any trace of the mobile SA-2 sites that once ringed Hanoi and made its airspace among the most heavily defended in the world, but examples of the missiles themselves aren’t hard to find in the Vietnamese capital. On the grounds of military museums in what was once called North Vietnam, they stand like the statues of Greek gods. As an American, seeing the weapons that shot down so many U.S. airmen was jarring, if not a little unnerving...