Fifty kilometers from Ho Chi Minh City, a withered trunk of a dead tree stands amid a mangrove forest in Vietnam’s Can Gio district.

The tree was preserved as a reminder of the damage caused by Agent Orange, a defoliant that was sprayed over wide parts of the nation by the U.S. military during the Vietnam War to deprive the Viet Cong of cover.

According to research conducted by the United States, Agent Orange was sprayed over 2.63 million hectares of land in Vietnam, releasing about 366 kilograms of highly toxic dioxin into the environment.

The chemical has caused an increase in cancer among Vietnamese and babies suffering from congenital disabilities.

Nguyen Duc and Viet were twins born conjoined, apparently as a result of the use of Agent Orange. They were surgically separated in Ho Chi Minh City, but Viet died of natural causes in 2007.

Dioxin affects reproductive functions, and experts have pointed to the dangers of disabilities and illnesses being passed down from parent to child.

According to the Vietnam Association for Victims of Agent Orange/ Dioxin (VAVA), which receives support from the Vietnamese government, more than 3 million people in Vietnam still suffer from the after-effects of the defoliant. In 2012, a baby was reported to have suffered health problems related to the defoliant, meaning a fourth generation of victims had emerged.

Tran Thi Le Huyen, who is 29 and lives in Da Nang in central Vietnam, is a victim of Agent Orange. She has been bedridden since birth and her thin legs are bent.

Her mother, Thanh, 56, said, “We have visited various hospitals, but there was no place that offered any treatment.”

Da Nang International Airport is located about 10 minutes away by car. During the Vietnam War, the airport was the largest base for the U.S. military as its planes went on bombing missions. The area was polluted by Agent Orange that leaked from containers or that seeped into the ground after planes that sprayed the chemical were washed.

A 2009 study found areas in which about 20,000 picograms of dioxin were detected in a gram of soil. That is close to 20 times the environmental standard in Vietnam and Japan.

Huyen’s father, Thuan, and mother ate fish caught in a pond adjacent to the airport. High levels of dioxin were found in the fish. There is the possibility that dioxin flowed into the pond from the airport and accumulated as it went up through the food chain. Although there is still uncertainty about just how the process works, there is the danger that health effects could turn up in children, even though those who actually consumed the fish are not affected.

According to the Vietnamese government, there are at least 28 “hot spots” where high levels of dioxin have been found. Many are areas that were near U.S. military bases.

One such location is Dong Son village near the border with Laos. The A So base was once located there. While local authorities have installed barbed wire to keep people out, children on occasion have been known to play inside the polluted areas.

Although work began from 2012 in Da Nang to clean up the pollution through the cooperation of the United States, little has been done in other areas.

“As long as hot spots exist, victims will continue to emerge,” said VAVA’s vice president Tran Xuan Thu. “The war has still not ended.”

The Vietnamese government has been certifying victims since 2000, and providing support through the payment of benefits. However, so far the program has been limited to military veterans and their families. The benefits also only come to about several thousands of yen a month.

“A major issue will be improving the support program,” Thu said.

While some work has been done to replant forests destroyed by Agent Orange, the process is slow.

Almost the entire mangrove jungle in Can Gio of about 40,000 hectares was destroyed, leaving barren wasteland behind after the dead trees were swept away into the ocean. The monkeys, alligators and birds that used to live in the jungle, where the trees grew to a height of 20 meters, also disappeared.

After the Vietnam War ended, replanting began from 1978, and in 2000, UNESCO designated the area as a biosphere reserve. Only small amounts of dioxin that was sprayed on the forest remained in the soil, and what was left was washed away by rain and the tide. Saplings from the mangrove trees that survived were transported by boat and entire communities came out for the planting.

The Can Gio jungle has been restored to prewar conditions, but it cannot be said to have been restored quality-wise. Because mangrove types that grow quickly were chosen for the planting, and the planting was done quickly, vegetation has become uniform. With all the trees about the same height, sunlight does not reach the jungle floor. There is also heightened risk of disease because the tree density is too high.

“It will be difficult to return the jungle to a sustainable state,” said Phung Tuu Boi of the Vietnam Forestry Science and Technology Association, which has been involved in the replanting process. “Centuries will be needed to restore the destroyed environment.”

The use of Agent Orange marked the first time the chemical was used in actual warfare.