Tom Vanden Brook

USA TODAY

HO CHI MINH CITY — Army Gen. Martin Dempsey has served 40 years in the Army, fought in Iraq, traveled the world many times over.

None of that fully prepared him for his first visit to Vietnam — the first by a chairman of the Joint Chiefs of Staff since Adm. Thomas Moorer visited in 1971. At that time, there were 300,000 U.S. troops in Vietnam.

"Flying in, it's almost visually overwhelming," Dempsey told USA TODAY, which joined him on the trip. "The architecture. The mopeds. The images of modernity clashing with the past. Women in the fields tending to the rice patties, walking down the street with the pole and two buckets.

"So you've got this juxtaposition with who they've been and who they are now."

The war's imprint, though faint, still can be traced. Part of Dempsey's mission here was to acknowledge but not be shackled by the past as the once-bitter enemies seek new and deeper ties. Dempsey's four-day visit to three cities offered glimpses of the past, present and future of this country of 93 million people crowded into a space about the size of New Mexico.

A litany of past and present problems confronted Dempsey on the trip — from the toxic effects of the defoliant Agent Orange to the rise of China, whose muscular military response in the South China Sea has unnerved Vietnam and other countries in the region. The specter of the Vietnam War, and the 58,000 U.S. troops killed here, looms over all the issues, a reminder of the war the United States lost and the humiliating helicopter evacuation of diplomats and dependents from the roof of a U.S. Embassy building in May 1975. There are opportunities for increased trade for Vietnam, a country that has bounced back from war's devastation.

Dempsey's visit signals that the United States and Vietnam want to forge closer military ties, says Ernie Bower, an expert on Southeast Asia at the Center for Strategic and International Studies. Full diplomatic relations with the communist country were established in 1995, though a U.S. ban on selling weapons to Vietnam remains.

"The Vietnam War — or the U.S. War, as the Vietnamese call it — is fading fast in the rearview mirror," Bower says. The United States and Vietnam find common interests in developing a stable, peaceful and prosperous region, he says.

Dempsey saw a land evolving in ways small and big. Small: Luxury retailer Hermes bustles while relics such as '60s-era tanks and warplanes from the war rust and molder in the tropical heat and humidity. Big: Vietnam courts the United States, the superpower it booted out, as counterweight to China.

From north to south, signs of new nudging old abound. Just beneath a billboard touting bathroom fixtures from the U.S. plumbing giant Kohler is a woman in a field, wearing a conical hat and tending to emerald-green rice stalks.

DANANG: EXPIATING SINS OF WAR

The airport in this pretty port city in central Vietnam on the South China Sea has a very dirty but open secret. In the shadow of the modern terminal lies what would be known as a Superfund site in the USA. The U.S. Agency for International Development is cleaning up poisonous residue from 20 million gallons of herbicide sprayed to destroy crops that fed Viet Cong troops and the jungle foliage that concealed them. U.S. troops who set foot in Vietnam are eligible for treatment of ills linked to the toxin, Agent Orange.

This chemical scourge got its name from the stripe on its 55-gallon shipping drums and was a cocktail of herbicides containing dioxin. From 1962 to 1971, U.S. Air Force crews loaded the chemicals on planes at Danang Air Base. Cargo planes, much like crop dusters, sprayed Agent Orange on broad tracts of farmland and jungle.

In Danang, the defoliation mission, dubbed "Operation Ranch Hand," contaminated 95,000 cubic yards of soil. Dempsey toured the cleanup site, a sawed-off concrete pyramid that holds and heats the dirt until dioxin breaks down. The cleanup is scheduled to be complete in 2016.

An outside observer, Wallace "Chip" Gregson would like to see the United States step up its efforts to exorcise another deadly reminder — unexploded munitions. U.S. bombs and shells leveled chunks of Vietnam. Many didn't explode yet remain deadly.

Gregson, who fought in Vietnam as a young Marine, retired in 2005 as a three-star general. In 2009, he was named assistant secretary of Defense for Asian and Pacific Security Affairs, a post he held until April 2011. He visits Vietnam regularly and is an expert on the region for the Center for the National Interest.

The United States and Japan have technology to destroy the unexploded ordnance at the site, avoiding the hazard of removing it and blowing it up elsewhere, Gregson says. "We can and should provide some major help to them," he says. "Aiding Vietnam's rapid development seems an appropriate riposte to China, as well as fulfilling a moral obligation from the war."

HANOI: WHAT VIETNAM WANTS

It's a concern Dempsey hears time and again during his visit: What matters most to Vietnam?

"China, China, China," an academic tells him during a roundtable discussion with local think-tanks.

The most recent clash stems from China's claim to offshore mineral rights and islands in the South China Sea. China has moved a deep-sea oil drilling rig into disputed waters and sank a Vietnamese fishing boat near it in May.

Vietnamese reporters at a briefing quiz Dempsey about China and what help the U.S. military can provide. It's not a fray the United States is eager to join, he says. A prosperous China that treats its neighbors well is the U.S. goal. "We're not trying to make anybody choose between China and the United States," Dempsey says.

Vietnam and China have fought as many as 18 wars over 2,000 years, the most recent in 1979. That makes China a preoccupation for Vietnam, but it's not in Vietnam's interest to provoke a major conflict.

Instead, Vietnamese leaders want a deeper relationship with the United States that includes being a member of the Trans-Pacific Partnership, a trade deal being negotiated among 12 nations that promises to boost investment and exports.

The Vietnamese want a clearer picture of what's happening over the horizon in the South China Sea. Their military lacks the radar and other surveillance aircraft, which limits their ability to see what China and others are doing.

If the weapons ban is lifted, Dempsey says, the Pentagon could sell Vietnam's navy better tools for surveillance of the sea.

HO CHI MINH CITY: VIETNAM'S FUTURE

Ho Chi Minh City — once known as Saigon and named after the revolutionary who led North Vietnam to victory in 1975 — pulses with energy. Torrents of scooters course through the streets, joined in increasing numbers by luxury vehicles.

Dempsey said he expected to be greeted warmly in Ho Chi Minh City but was a bit surprised to find a similar reception in Hanoi.

"I didn't know if there would be lingering war legacy issues that would cause them to be suspicious of us," Dempsey said. Instead, he found "that their population has in fact moved on. I'm sure not all of them, by the way."

Economic growth, which had buzzed at high rates for years, has slowed since 2008. Corruption throttles foreign investment and chokes growth, according to studies by the U4 Anti-Corruption Resource Center.

Vietnam joined the Trans-Pacific "negotiations in part because it needs to reform its economy to compete effectively and in part because it realizes that economic engagement is the foundation for a strong security relationship," Bower says.

If Vietnam gets its act together, the country could be another South Korea, according to government reports, including one by the United Kingdom's trade and development agency in July. Helping Vietnam could benefit the United States.

"It occurred to me oftentimes that adversaries in our past can become our closest friends," says Dempsey, 62, who graduated West Point in 1974, too late to go to the war.

"That's not to say it won't happen without some effort. But I think there's a possibility that Vietnam could be a very strong partner. Look at our history with the British or the Germans or the Japanese. It could be like a phoenix rising from the ashes. That's what I hope happens here in this relationship."

Follow @tvandenbrook on Twitter.