FOR GEORGE W. BUSH, it would be bizarre if the most loyal and gifted member of his cabinet were to be the instrument of his defeat in November 2004. Recent developments on the Iraq front of the war on terror make such thoughts about Defense Secretary Donald Rumsfeld harder and harder to put aside.

No, it isn't about the prison scandal. Bad as this is, a successful execution of the president's Iraq strategy will in the end render Abu Ghraib an ugly sideshow.

The danger to the Bush presidency lies in the decision to pull the Marines back from attacking Sunni terrorists in Falluja, and the growing probability that similar avoidance of U.S. military risk is being adopted in other parts of Iraq. This sends the worst conceivable signal to Iraqi advocates of democracy and would-be political leaders.

The incentives are simple, and widely understood: Take seriously the Bush strategy of democratization, supporting the occupation and sticking to peaceful advocacy, and you become an immediate candidate for assassination. Take up the weapons of terrorism, have a measure of success in the arts of murder and desecration, and the United States will soon be negotiating to put you in charge of "security" in your area--even if you are a former Baathist general still sporting a Saddam-style moustache.

Why is this happening? Is President Bush a Machiavellian, giving idealists the rhetoric and quietly awarding Huntington-style cultural chauvinists and Arab oligarchs the substance? Such massive deception is neither likely nor even very plausible for a president who doggedly continues to defend his vision of democratic renewal in the Arab and Islamic world, in the face of humiliating setbacks and ridicule from Mideast experts. If Bush were the sort of president willing to tolerate pleasant lies in search of favorable editorials, he long since would have resumed the endless farce of U.S.-led peace negotiations with Yasser Arafat.

Nor does the Falluja incentive system seem to stem from any grassroots revolt of the uniformed military against the Bush policy. By most accounts, the Marine units in Falluja were eager to crush the terrorists who had killed Americans and desecrated their bodies and were unhappy at the order to pull back. Besides, no defense secretary in memory has exercised greater control over ground execution than the brilliant, hands-on Rumsfeld. He may not be loved by the uniforms, but they know better than to try to sabotage the man who ordered the headlong rush to Baghdad a year ago, and was proven right by the astounding results.

A clue to what may be going on is Rumsfeld's recent, and rare, confession of unpleasant surprise at the number of U.S. casualties taking place a full year after the fall of Baghdad. Rumsfeld was an elective politician in the 1960s. His first stint as defense secretary began nearly three decades ago, just a few months after the North Vietnamese conquest of South Vietnam. It is a commonplace that the Vietnam experience turned many American hawks into doves or isolationists. Less well understood is what it did to those American hawks who never stopped being hawkish.