The Vietnam War may have ended almost 40 years ago, but the United States is just getting around to cleaning up a sad legacy if left in the southeast Asian country -- the remnants of the toxic herbicide Agent Orange.

The $49 million cleanup begins Thursday at the former U.S. military base of Da Nang, the Associated Press reported Wednesday. While the U.S. has previously shelled out billions of dollars in disability payments to American soldiers who developed illnesses associated with the defoliant - its active ingredient is dioxin, which has persistently been linked to cancer and multiple birth defects - this marks the first occasion the nation has made a move to clean up the approximately 20 million gallons of Agent Orange it dumped on Vietnamese trees and vegetation in the decade between 1961 and 1971.

The herbicide destroyed approximately 5 million acres of forest and another 500,000 acres of crops. The Vietnam Red Cross estimates that at least 3 million Vietnamese citizens have experienced health problems due to exposure to Agent Orange, including about 150,000 children with birth defects. In addition to direct exposure during the spraying itself in the 1960s and 1970s, individuals are still being exposed to dioxin through contaminated soil, sediment, water and livestock.

According to the report, the cleanup efforts will focus on three specific "hot spots" -- the former U.S. air bases in Da Nang, Bien Hoa and Phu Cat, where Agent Orange was mixed, stored and loaded onto planes.

While the U.S. has been quick to acknowledge the issues faced by servicemen exposed to the defoliant, it has been reluctant to confirm that up to 4 million Vietnamese were also affected by the toxic chemicals, alleging that other environmental factors could be to blame for their health issues. In fact, as recently as 2010, a Congressional Research Report analyzing the effects of Agent Orange in the country refers to "the Vietnamese government's" concern about the health affects of the herbicide, but does not acknowledge it as fact.

But that dispute may have cooled, as US Defense Secretary Leon Panetta indicated in June.

"We had a complicated relationship, but we're not bound by that history," Panetta said during a visit to Hanoi.

Of course, U.S. leaders have their own reasons for finally making the move. The AP reports the U.S. hopes to stave off China's rising influence in the South China Sea by boosting trade with Vietnam and forging a stronger alliance with the country it once coated with toxic chemicals (they were meant to deprive Vietcong guerrillas of jungle cover and expose them to U.S. bombing.)

But while Congress has reportedly appropriated $49 million toward environmental remediation in the country and another $11 million to help people living with disabilities there -- regardless of the cause -- in May, the U.S.-Vietnam Dialogue Group estimated it may take upwards of $450 million to clean up dioxin hot spots, provide services to individuals with disabilities, and restore damaged landscapes over the next five years.