WASHINGTON — Why was Air Force Chief of Staff Michael J. Dugan canned?

An angry Defense Secretary Dick Cheney publicly catalogued Dugan's sins on Monday: revealing classified war plans, demeaning the other military services, underestimating the enemy, treating casualties in a cavalier manner. Cheney was especially disturbed by Dugan's assertion that the United States intended to seek out Iraqi leader Saddam Hussein, his family and his palace guard as targets of an intense air campaign.

These are serious offenses, especially for a member of the Joint Chiefs of Staff, and especially as the nation teeters on the brink of war.

But a number of other, more subtle factors were at play in the Dugan affair that combined to bring about his downfall.

By discussing possible military targets inside Iraq, Dugan took upon himself decisions that are reserved for the President--a violation of the chain of command that Cheney believed he could not tolerate.

The Air Force chief also may have complicated the military operation by telling Iraq's Hussein what sites would be targeted, allowing Hussein to place American hostages there.

In addition, Dugan discussed sensitive matters of Israeli cooperation in the American military effort, a definite taboo in an operation that depends heavily on Arab unity.

But perhaps his greatest transgression was saying what he thought and letting himself be quoted saying it--a mortal sin in this Administration, which jealously guards policy-making power and tightly controls the flow of information to the public.

By allowing himself to be quoted on the record, Dugan squandered the precious commodity of "deniability" and forced Cheney and other Administration officials to respond.

The brotherhood of combat fighter pilots, from which Dugan rose, does not generally appreciate the subtleties of the Washington game as played by such seasoned professionals as Cheney and Gen. Colin L. Powell, chairman of the Joint Chiefs.

Unfortunately for Dugan, the art of the background leak and the trial balloon are not on the curriculum of the Air War College.

Dugan's reward for his years of prowess in the cockpit was a seat on the Joint Chiefs of Staff, where he found the rules of engagement to be far more ambiguous, and far more lethal, than anything he had encountered in his 32-year Air Force career.