In many ways, Nguyen Thi Ly is just like any other 12-year-old girl. She has a lovely smile and is quick to laugh. She wants to be a teacher when she grows up. She enjoys skipping rope when she plays.

But Ly is also very different from other children. Her head is severely misshapen. Her eyes are unnaturally far apart and permanently askew. She’s been hospitalized with numerous ailments since her birth.

Her mother, 43-year-old Le Thi Thu, has similar deformities and health disorders. Neither of them has ever set foot on a battlefield, but they’re both casualties of war.

Le and her daughter are second- and third-generation victims of dioxin exposure, the result of the U.S. military’s use of Agent Orange during the Vietnam War, when the U.S. Air Force sprayed more than 20 million gallons of Agent Orange and other herbicides over parts of southern Vietnam and along the borders of neighboring Laos and Cambodia. The herbicides were contaminated with dioxin, a deadly compound that remains toxic for decades and causes birth defects, cancer and other illnesses.

To this day, dioxin continues to poison the land and the people. The United States has never accepted responsibility for these victims – it denies that Agent Orange is responsible for diseases among Vietnamese that are accepted as Agent Orange-caused among American veterans – and it’s unclear when this chain of misery will end.

On Thursday, President Barack Obama will meet with Vietnamese President Truong Tan Sang at the White House, only the third meeting between chief executives of the two countries since Vietnam and the United States established diplomatic relations in 1995.

The two countries share many contemporary concerns. The White House says Obama plans to discuss cooperation on regional issues and trade, plus other U.S. priorities such as climate change and human rights. The two countries share a strong common interest in countering China, which has become increasingly assertive over potentially oil-rich areas of the South China Sea.

Many Vietnamese say it’s time for the United States to do more to address the issue of Agent Orange and its victims, so that the last tragic chapter of the Vietnam War finally can be closed.

Le Thi Thu’s father served in the North Vietnamese army and was wounded in Quang Tri province, one of the most heavily sprayed areas of the country.

“Before he went to war, my father had two children: my older brother and sister,” said Le, who was born in 1970. “They were normal. But after he came back, he had me.”

“I could see the differences in myself and others right away,” she recalled. “When I was a small child, I felt pain inside my body all the time. My parents took me to the hospital, and the doctors determined that I had been affected by Agent Orange.”

When her daughter Ly was born, “we knew right away” Agent Orange was to blame, Le said.

The Vietnam Red Cross estimates that Agent Orange has affected 3 million people spanning three generations, including at least 150,000 children born with severe birth defects since the war ended in 1975.

“During the war, we were hostile, but after the war ended, we normalized our relations and are now building a strategic partnership between Vietnam and the United States,” said retired Col. Thai Thanh Hung, the chairman of the 16,500-member Da Nang Veterans Association. “We no longer have hatred towards the Americans and the U.S. government, but we want this one lingering and remaining issue to be addressed, which is that the United States help solve the Agent Orange and dioxin problem. That’s why we’re keeping an eye on this issue, to see if the United States is really interested in healing the wounds or not.”

The most significant event to date occurred last August – 37 years after the war ended – when U.S. contractors began a project to remove dioxin from 47 acres of contaminated soil at the Da Nang International Airport, which was one of the largest U.S. bases during the war.

The $84 million effort, which is expected to take until the end of 2016 to complete, has been hailed as an important milestone in U.S.-Vietnamese relations. The airport is one of the most heavily contaminated areas in the world, with dioxin levels measuring more than 365 times the acceptable limits set by the United States and other industrialized countries.

Observers say that while the project represents a long overdue first step, more work needs to be done. More than two dozen other known or potential dioxin “hot spots” have been identified at former U.S. bases. Also left unresolved is the thorny issue of how best to help Vietnamese who’ve been sickened and disabled because of Agent Orange and dioxin exposure.

U.S. aid for these people so far has amounted to a pittance. According to the U.S. Embassy in Hanoi, only $11 million of the $61.4 million that Congress has allocated since 2007 – a year after then-President George W. Bush pledged to help clean up contaminated areas – has been earmarked for public health programs in Vietnam.

U.S. officials caution that the money is to help people with disabilities “regardless of cause,” and isn’t specifically for Agent Orange victims. This semantic sleight of hand outrages many American veterans of the war, who say the United States has a moral obligation to help Vietnamese victims of Agent Orange, just as sick and dying U.S. veterans have received government help for the last two decades.

“There’s a hypocrisy there,” says Chuck Searcy, who served in Vietnam as an intelligence analyst during the war and has lived in Hanoi since 1998, heading up a project to clear battlefields of unexploded ordnance, which also continues to kill and maim Vietnamese. “It’s a glaring disconnect, and it’s embarrassing because the whole world can see it.”

The U.S. Department of Veterans Affairs says that all 2.8 million Americans who served “boots on the ground” in Vietnam from 1962 to 1975 were exposed to Agent Orange and other herbicides, which were in use from 1961 to 1971. They qualify for compensation if they become sick from any of 15 illnesses presumed to have been caused by their exposure. The VA also recognizes another 18 birth defects in the children of female veterans.

In 2011, the last year for which data was published, the VA paid nearly $18 billion in disability benefits to 1.2 million Vietnam-era veterans, including 303,000 who received compensation for diabetes mellitus, the most common of the 15 diseases associated with herbicide exposure.

U.S. officials have long held, however, that there’s no proof that Agent Orange is to blame for the same diseases and birth defects in Vietnam.

“Few independent studies have been conducted in Vietnam to assess possible health effects on the local population,” said Chris Hodges, a spokesman for the U.S. Embassy in Hanoi. “The lack of validated data and scientific review makes it difficult to estimate accurately the number of actual or potentially affected people or the extent of related health effects.”

In many ways, the fight for recognition of Vietnam’s Agent Orange victims mirrors the 20-year struggle that U.S. veterans endured before Congress granted them compensation in 1991.

Hoping to emulate a case that resulted in a 1984 settlement requiring Dow Chemical, the Monsanto Corp. and other Agent Orange manufacturers to pay $197 million in damages to sick U.S. veterans, a group of Vietnamese victims sued in 2004, only to have the same federal judge dismiss their case a year later, saying the companies were immune because they were following government orders. The Supreme Court declined to hear the case in 2009.

As occurred with U.S. veterans, momentum in Congress appears to be shifting favorably toward the Vietnamese. In 2011, lawmakers directed the U.S. Agency for International Development to develop a plan for assisting Vietnam with Agent Orange programs in the coming years. The agency hasn’t yet released its proposals.

For its part, Vietnam has put into motion a set of steps that it says will “fundamentally solve” its problems with Agent Orange by 2020. The document, signed in June 2012 by Prime Minister Nguyen Tan Dung, outlines preferential treatment for all ailing veterans who fought against the Americans, monthly stipends and health coverage for families with disabled members and special care for pregnant women from contaminated areas.

The Aspen Institute, a Washington-based research center, has called on the United States to spend $450 million over 10 years to clean up Vietnam’s dioxin hot spots, restored damaged ecosystems and expand health care for people with disabilities.

It’s unclear how much Congress is willing to do. Rep. Barbara Lee, D-Calif., introduced a bill last month that would commit the United States to cleaning up all remaining sites and would provide assistance to help Vietnam give better health care and other resources to Agent Orange victims. An identical bill introduced two years ago failed to make it out of committee.

Searcy, the former intelligence analyst who lives in Hanoi, points out that after nearly 40 years, Vietnam’s expectations of the United States remain modest.

“The Vietnamese have never demanded that the U.S. do for the Vietnamese what they’ve done for U.S. veterans,” he said. “But the Vietnamese have left the door open to do what’s fair.”

“I think it’s possible to bring some closure to this within the next decade,” he added.