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The U.S. is still on the hunt for terrorists in the first war of the 21st century, and it will not let Iraq aid those thugs, President Bush said at an East Room ceremony celebrating Veterans Day.

"Saddam Hussein will fully disarm and prove that he has done so or America will lead a coalition to disarm him," Bush said. "I will commit the full force and might of [the] U.S. military and we will prevail."

Later at the Tomb of the Unknown Soldier in Arlington Cemetery, the president repeated his vow that the United States will not be cowed by a despot.

"This great nation will not live at the mercy of any foreign plot or power," he said, after laying a wreath in front of the sarcophagus.

Behind the scenes, Bush has approved tentative Pentagon plans for invading Iraq should a new U.N. arms inspection effort fail to rid the nation of weapons of mass destruction. The strategy calls for a land, sea and air force of 200,000 to 250,000 troops, administration officials said.

"We have to keep, in a sense, a gun pointed to the head of the Iraqi regime because that's the only way they cooperate," Bush's national security adviser, Condoleezza Rice, told National Public Radio's The Tavis Smiley Show.

The talk of war grew to a crescendo just three days after the U.N. Security Council approved a tough new resolution with an unexpected 15-0 vote. Iraq has until Friday to accept the resolution that would send U.N. inspectors back to Baghdad after an absence of nearly four years with broad new powers to go anywhere at any time backed by the threat of force.

After laying the wreath at the Tomb of the Unknowns, Bush praised America's veterans and pledged his resolve against terrorism and Iraq.

"We will not permit a dictator who has used weapons of mass destruction to threaten America with chemical, biological or nuclear weapons," the president said.

Standing beneath the marble dome of the cemetery's flag-draped amphitheater, the president drew cheers and whistles of approval when he declared, "The dictator of Iraq will fully disarm or the United States will lead a coalition to disarm him."

Defense Secretary Donald H. Rumsfeld said the most dangerous threat of current times is that of countries like Iraq giving nuclear, chemical or biological weapons to international terrorists.

"The only way to confront terrorists with weapons of mass destruction is to stop them before they attack," Rumsfeld told a group of business executives meeting in Washington.

Rumsfeld said Iraq had hidden its weapons at sites throughout the country. "They have tunneled underground. It's going to be very difficult for inspectors to find anything," he said.

The secretary said he had no doubt that the United States would prevail in the event of war. He said a postwar Iraq would have to remain a single country and have "some sort of representative government."

"It will be something that is distinctly Iraqi," he said.

In Baghdad, Iraq's parliament condemned the U.N. resolution as full of lies, and a senior lawmaker urged that it be rejected — a prospect that likely would bring on war.

Rice dismissed the response and the parliament itself.

"I don't think anyone believes this is anything but an absolute dictatorship and this decision is up to Saddam Hussein," she told reporters at the White House.

Even if Saddam accepts the resolution, Rice said she will remain skeptical.

"They are obligated to accept, but the U.N. thought it best to ask for return-receipt requested," she said.

Bush himself said Iraq is behind the eight-ball.

"No enemy that threatens our security or endangers our people will escape the patient justice and the overwhelming power of the United States of America," he said in the East Room.

Bush began his day with a pre-dawn visit to the Vietnam War Memorial. As a chilly rain pelted his umbrella, Bush placed an American flag at the base of the black granite wall, where 58,229 names of those killed or missing in the war from 1959 to 1975 are inscribed.

Later, at the East Room reception, Bush said America owes its freedom to the ex-soldiers gathered before him and its greatness to their postwar service. "Our veterans from every era are the finest of citizens," the president said. "We owe them the life we know today."

He carried the theme to the cemetery, where white headstones honor 260,000 American heroes.

"We remember those who served America by fighting and dying on the field of battle, and we remember those veterans who lived on for many decades to serve America in many ways," Bush said.

Fox News' Wendell Goler and The Associated Press contributed to this report.