President Bush is methodically laying the foundation to overthrow Iraq's Saddam Hussein, perhaps with military action, and he may feel compelled to strike without warning.
In recent weeks, the administration has intensified its rhetoric against Saddam and unveiled a new policy that calls for pre-emptive action against enemies armed with weapons of mass destruction.
Aides say Bush's resolve has not been weakened by the Mideast crisis, tension in southeast Asia or qualms of U.S. allies.
Behind closed doors at the White House, the president reacted with dismay to reports that U.S. military leaders were lobbying against an Iraqi invasion anytime soon.
"I don't know what they're talking about," two senior U.S. officials quoted the president as saying. They interpreted the remark to mean Bush is seriously considering military action despite opposition.
Bush himself told supporters this week: "When we see evil -- I know it may hurt some people's feelings, it may not be what they call diplomatically correct -- but I'm calling evil for what it is. Evil is evil, and we will fight it with all our might."
Bush may choose diplomatic pressure or covert action to undermine Saddam. If he decides to go to war, there will be more choices -- such as whether to follow his father's blueprint or launch an unconventional attack.
Most analysts assume Bush would slowly generate support inside and outside the country with a series of warnings to Saddam and a deliberate marshaling of U.S. troops. After all, the world saw the Persian Gulf War coming for six months before Bush's father ordered the attack.
But there may be little or no warning this time.
If the United States' estimation of Iraq's weapons of mass destruction program is correct, a long buildup to war could be catastrophic, analysts say.
Given notice, Saddam might strike the United States first or help a terrorist group do so. He could become cornered and desperate -- and presumably armed with a greater arsenal of deadly weapons than he had during the Gulf War.
"We're now beginning to understand that we can't wait for these folks to deliver the weapons of mass destruction and see what they do with them before we act," said Philip D. Zelikow, a University of Virginia history professor who worked for the National Security Council under Bush's father.
"And we're beginning to understand that we might not want to give people like Saddam Hussein advance warning that we're going to strike," he said.
Saddam, meanwhile, is showing more aggressiveness. On Friday, U.S. aircraft bombed an Iraqi military facility in response to an Iraqi attack the previous day on aircraft patrolling the southern "no-fly" zone. It was the fourth such strike in a month.
Some top military leaders favor delaying an Iraqi invasion until next year and perhaps not do it at all. They warn that at least 200,000 troops would be needed. They want the focus to be on covert intelligence operations.
But if Bush decides to strike without warning, there are alternatives to a conventional military buildup.
One strategy first proposed by retired Army Gen. Wayne A. Downing four years ago calls for attacking Iraq with a combination of airstrikes and special operations attacks in coordination with Iraqi fighters opposed to Saddam.
From Kuwait, carrier battle groups in the nearby waters or Kurdish-controlled northern Iraq the forces could launch surprise attacks against the nation's weapons facilities -- or even target Saddam himself.
A sneak attack would create a huge uproar in the international community and expose Bush to criticism at home, particularly if troops get bogged down in a post-Saddam Iraq.
Leaving a White House meeting with Bush, Sen. Joseph Biden, D-Del., chairman of the Senate Foreign Relations Committee, said he told Bush: "There's a reason why your father stopped and didn't go to Baghdad."
Under his new policy, which has evolved since the Sept. 11 attacks, the U.S. military can take pre-emptive action, if necessary, against terrorist-harboring nations that have weapons of mass destruction.
Iraq may fit the bill:
-- Bush increasingly suspects that Saddam still supports terrorism, despite repeated warnings since Sept. 11.
-- Defense Secretary Donald H. Rumsfeld recently dismissed claims by the Iraqi government that it has no nuclear, chemical or biological weapons. "They are lying," Rumsfeld said.
The president's views toward Iraq have hardened since Sept. 11, when he condemned terrorist-harboring nations but did not mention weapons of mass destruction.
On Nov. 16, he warned for the first time that Osama bin Laden was seeking chemical, biological and nuclear weapons. He had been told that al-Qaida may have access to those weapons through Pakistan.
The chilling news is said to have crystallized Bush's thinking that terrorist groups and nuclear nations are a deadly combination.
That led to the State of the Union address and Bush's outing of an "axis of evil" -- Iraq, Iran and North Korea.
Standing before Congress, he offered the first hint of his "strike first" doctrine and, perhaps, his plans for Iraq.
"I will not wait on events while dangers gather," Bush said.