Facing a US-led invasion, will Saddam Hussein order chemical and biological weapons attacks on US troops - or even on his own people as a propaganda ploy? Will he decide to set Iraqi oil fields ablaze? Will he order Scud missile attacks on Riyadh, Tel Aviv, or other cities?
Simply put, once his regime is doomed, will Mr. Hussein go out with a wave of vengeful destruction?
Pentagon planners must assume the answer is yes.
Indeed, months ago, Defense Secretary Donald Rumsfeld drafted a list of "risks of acting" to overthrow Hussein and presented it to President Bush. Top US military officials added to the list, which now runs four or five pages, and are readying countermeasures.
Whether or not the United States can avert such worst-case scenarios remains in doubt, however, especially if Hussein chooses to wreak havoc on his own country, say military officials and analysts.
One potential catastrophe would involve the successful Iraqi use of chemical or biological agents. US officials believe the Baghdad regime is preparing to use weaponized agents against American forces and possibly against civilians in neighboring countries or in Iraq.
"[There is] concern about Saddam Hussein using weapons of mass destruction against his own people and blaming it on us, which would fit a pattern," Defense Secretary Donald Rumsfeld said recently.
The Iraqi military last fall began dispersing rocket launchers and warheads filled with biological agents in western Iraq. It hid the launchers in large groves of palm trees, with plans to move them every few weeks to escape detection, according to US intelligence cited by Secretary of State Colin Powell last week. Hussein recently authorized field commanders to use the weapons, he said.
Washington is trying to discourage such attacks in two ways: First, it has vowed to bring to justice any Iraqi who obeys orders to use "weapons of mass destruction" (WMD). It is uncertain, however, whether such a warning will influence hardened Hussein loyalists.
Second, the Bush administration has pointedly retained the option of nuclear retaliation. "I'm not going to put anything on the table or off the table, but we have a responsibility to make sure Saddam Hussein and his generals do not use weapons of mass destruction," Andrew Card, White House chief of staff, said recently.
Nevertheless, whether the United States can make the nuclear deterrent credible in the case of Iraq remains in doubt.
Prior to the 1991 Gulf War, US officials publicly hinted of the threat of nuclear retaliation if Hussein used WMD or ignited Kuwaiti oil fields - but failed to carry out that threat when the oil wells were set on fire. Indeed, privately, the nuclear option had been all but ruled out by senior US officials including Colin Powell, chairman of the Joint Chiefs of Staff.
Today, some US officials are downplaying the nuclear deterrent. "I think we believe we have all the capabilities we need with our conventional forces," said Deputy Defense Secretary Paul Wolfowitz.
Also, the political threshold for using a nuclear weapon remains extremely high. "The president would really have to pause to be the first person to use a nuclear weapon in more than half a century," notes Hans Binnendijk, a nuclear-arms expert at the Pentagon's National Defense University.
Moreover, the US currently lacks a small, low-yield nuclear device suited for striking deep bunkers, he says.
Should Iraq launch a chemical or biological weapons attack using artillery shells or airborne vehicles, US troops are well equipped to deal with it. With protective masks, suits, and the ability to quickly counterattack, US forces would likely be slowed but not stopped by such weapons.
"The most [Iraq] could get off would be a few rounds, and that would be choked off very quickly," says James Carafano, senior fellow at the Center for Strategic and Budgetary Assessments here.
Civilian populations in Iraq and elsewhere would be highly vulnerable to the toxic weapons, however. "In urban areas, the civilians would take the brunt of the casualties," Mr. Carafano says.
Another disaster could result if Hussein decides to blow up some of Iraq's 1,500 oil wells. Military movements in Iraq's southern and northern oil fields indicate the regime may have begun wiring oil heads to be destroyed - just as it destroyed Kuwaiti oil fields in 1991, according to a senior US military official.
The cost of such an "act of terrorism" could range from $30 billion to $50 billion in infrastructure repair as well as billions more in lost Iraqi oil revenues and environmental damage. Smoke, soot, and sulfur from the blaze would only temporarily divert US forces, but it could have long-term health impacts for Iraqis, he says.
US military planners are working on options to "preserve and protect" the fields. Still, if the wells are prewired to detonate, the American forces may not be able to act quickly enough.
A third contingency preoccupying US military planners is the possibility - recently underscored by Iraqi threats - that Iraq will launch Scud missiles at neighboring states. Iraq is believed to have at most a few dozen Scud or Scud-type missiles with ranges of 150 miles to 400 miles - capable of striking Israel, Turkey, Kuwait, and Saudi Arabia.
While often faulty and inaccurate, the missiles nevertheless are lethal. In the Gulf War, Iraq fired dozens of such missiles at Israel and Saudi Arabia, killing an Israeli citizen and 28 American servicemen.
Today, US commanders hope the latest technology will allow them to destroy the Scuds before they hit - a goal that proved elusive during the last Gulf conflict. The strategy includes having US Special Operations Forces on the ground seek out missile sites and call in airstrikes to destroy them. Unmanned aerial drones, such as the Predator, can also offer real-time surveillance of suspected sites.
If Iraq does launch Scuds, US forces would try to shoot them out of the sky with new Patriot missile-defense systems. The Army's truck-mounted, "hit-to-kill" PAC-3 missile systems have performed well in experiments but remain untested in battle. "A combination of significantly improved Patriots ... plus better suppression capability with the Predators gives you a good chance of being able to prevent anything from getting to Riyadh or Tel Aviv," says retired Air Force Col. John Warden, who planned US air strategy in the Gulf War.