Larry Zimmerman at a meeting of the Military History and Veterans Discovery Group. On the screen behind him is a North Vietnamese poster celebrating truck drivers on the Ho Chi Minh Trail. (John Kelly/The Washington Post)

It was a complete coincidence that Larry Zimmerman’s lecture Tuesday to the Military History and Veterans Discovery Group took place on the very same day President Obama was in Laos announcing $90 million in U.S. aid to help clean up millions of unexploded bombs the United States dropped nearly 50 years ago.

Larry’s talk was scheduled months ago. Its title: “The Laotian Interdiction: An Aspect of the Air War in Vietnam.”

Larry was an aspect of that aspect of that air war. In 1969, he was a 26-year-old Air Force captain stationed at Nakhon Phanom Royal Thai Air Base in northeast Thailand, where some of the elements of a secret bombing campaign against Laos were overseen.

Because Larry would be using an overhead projector to show dozens of old-fashioned transparencies, his talk was jokingly billed as “period-correct.” He said it was just because he didn’t trust PowerPoint not to crap out on him.

Marshall Sneiderman, left, and Larry Zimmerman talk after Zimmerman’s lecture on the U.S. bombing campaign in Laos during the Vietnam War. (John Kelly/The Washington Post)

Larry put up his first transparency, a map of Southeast Asia. Snaking down North Vietnam and into Laos and Cambodia was the Ho Chi Minh Trail, the route the communist North used to ferry men and materiel into South Vietnam.

The military history buffs meet monthly at the Margaret Schweinhaut Senior Center in Silver Spring, Md. On Tuesday, there were about 30 attendees, mainly men, most older, some veterans of the Vietnam War. Each man knew his own little part of that war — the view from a Navy ship in Haiphong Harbor or from the banks of the Mekong Delta — but, nearly 50 years later, was curious about the other bits.

“ ‘Trail’ is cute, but it’s not accurate,” said Larry, 73, of Rockville, Md. The Ho Chi Minh Trail wasn’t some tiny goat track but a highway, cleverly concealed in places, with depots and repair facilities.

Larry was assigned to Task Force Alpha, an outfit that worked in secrecy at the edge of the Thai air base on Operation Igloo White. Nifty little camouflaged spikes called ADSIDs — air-delivered seismic intrusion detectors — were dropped from airplanes and buried themselves in the ground near the trail. Topped with antennae, they picked up the rumble of heavy vehicles. Some had microphones and could relay the sounds of trucks, the chatter of troops.

And when the enemy was detected, the U.S. bombers and gunships came in. It’s estimated that 270 million bombs were dropped on Laos.

Sometimes, Larry said, a closer look was called for and he’d request RF-4C Phantom reconnaissance jets out of Udorn, Thailand. That’s the plane my father flew in the Vietnam War, and it’s possible that Larry looked at some of the pictures my dad took.

Larry placed another transparency on the projector. It showed the aftermath of a bombing run, a patch of jungle turned into a moonscape of bomb craters.

“All the photos were in black and white,” Larry said. “We joked it was a black-and-white country.”

Someone asked why the United States didn’t just bomb the enemy trucks when they were in North Vietnam, before they got to Laos.

“Politics,” someone said.

(We would bomb North Vietnam, eventually.)

Someone else asked whether it was true that President Lyndon B. Johnson would bigfoot his generals, choosing bombing targets himself.

“This was a micromanaged war,” someone offered.

It was a war we were winning for a while, and then we weren’t.

“All we did wasn’t enough,” Larry said as he turned off the projector to cool. “They outwaited us. It cost them a heckuva lot of people, a heckuva lot of trucks, a heckuva lot of money.”

It cost us, too. Larry said he thinks often of the 58,000 Americans who died during the Vietnam War.

It seemed I ought to ask Larry whether he ever thought of the people on the other end of those seismic sensors, on the other end of those bombs, of the people unseen in the photographs my father took. Larry said that Laotian civilians would have stayed away from the Ho Chi Minh Trail, knowing it was a free-fire zone.

Still, most estimates put the number of Laotians killed during the war at 250,000. Laos has been called the most-bombed country on Earth.

“It was your job; you didn’t worry about it,” said Larry, who after the war left the Air Force, joined the Army Reserve and spent 30 years working for the park and planning agency in Prince George’s County. “I hate to sound cold and ruthless, but we’re professionals. It goes with the turf.”

Even with all our technology — the microphones, the planes, the bombs — the weather dictated everything. When the rain came, neither side could do anything. Larry saw Obama on the TV news when the president arrived in Vientiane, the Laotian capital. There was a sea of umbrellas. The president carried one, too.

It reminded Larry of when he was in Southeast Asia. Forty days it rained in the summer of ’69, he said. Monsoon rains for 40 straight days, the heavens emptying. It still seemed unbelievable.

Twitter: @johnkelly

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