WASHINGTON (CNN) -- The retired former chief of U.S. Naval Operations in Vietnam, Admiral Elmo Zumwalt, is calling for immediate U.S. support for medical research in Vietnam into the health impact of Agent Orange.

Zumwalt, who played a key role ordering the aerial spraying of the defoliant from 1962 to 1971, says there is a compelling need to study the population most affected by long-term exposure to the plant-killing chemical.

He told a news conference Monday that American service personnel and their families deserve to have the most comprehensive medical database possible. Zumwalt noted the last wartime spraying was nearly 30 years ago, and that there's a risk of losing the opportunity to study its effects on a specific, well-controlled population.

Zumwalt believes that as health concerns first arose about Agent Orange years ago there was an effort to block detailed research needed to completely learn how U.S. veterans might have been affected.

"Those early years, the cabal urged creation in the Reagan administration of an Agent Orange coordinating task force, which had as its assignment the manipulation of government studies," Zumwalt said.

He quoted Reagan-era memos signed by a ranking budget official that Zumwalt says discouraged making any link between Agent Orange and disease. According to Zumwalt, the memos felt "it would be costly for the government to support the veterans," and that "corporations would be exposed to tort liabilities."

Zumwalt blames exposure to Agent Orange and dioxin for the cancer death of his son, Navy veteran Elmo R. Zumwalt, III.