Odom, who served in the administrations of former presidents Jimmy Carter and Ronald Reagan, died May 30 at his vacation home in Lincoln, Vt., The Washington Post reported. Odom's wife said he died of an apparent heart attack, but an autopsy was scheduled to determine the cause of death.
Odom, an acknowledged authority on the Soviet Union, served as military assistant to Carter's national security adviser, Zbigniew Brzezinski. Odom then served as director of the National Security Agency under Reagan.
Although he was known for opposing any compromise with the Soviets, Odom was "probably the first" senior U.S. military figure to oppose the Iraq War, Brzezinski told the Post.
"He believed that we're just stoking hostility to the United States in that region and developing an opposition that cannot be defeated by military means," Brzezinski said.
Odom warned before the March 2003 invasion of Iraq that the operation would not succeed. He wrote in the Post in February 2007 that President George W. Bush's Iraq policy was "based on illusions, not realities."
"There never has been any right way to invade and transform Iraq," Odom said.