Vowing to do what it takes to prevent attacks on America from potentially hostile nations, President Bush said Wednesday that Washington will keep "all options on the table" — including the use of nuclear weapons.

The U.S. nuclear arsenal is "a way to say to people who would harm America: 'Don't do it,"' Bush said at a press conference.

Bush was defending the Pentagon's reworking of its nuclear-weapons policy, which includes potential strikes against non-nuclear states like Iran and Iraq.

"We've got all options on the table because we want to make it very clear to nations that you will not threaten the United States or use weapons of mass destruction," he said.

But those countries the United States no longer considers hostile, at least officially, have been alarmed by the Pentagon's developing new policy. Russia and others supporting the U.S. war on terrorism feared that it might lower the threshold for when the U.S. will and won't use nuclear weapons. Others feared it might mean the Pentagon could target low-yield nuclear bombs against states such as China, Libya or Syria.

But "we're not out to seek revenge" — only justice, Bush said.

And, if anything, America's partners in the war on terror ought to take heart that the U.S. is demonstrating its seriousness with the policy, Bush added.

"If the United States were to waver, some in the world would take a nap when it comes to the war on terror and we're just not going to let them do that," he said. 

Vice President Dick Cheney is in the Middle East this week trying to rally Arab support for a tougher stance against Iraq, Bush said.

"One of the things I've said to our friends is that we will consult. ... In regard to Iraq, we're doing just that," he said.

Bush declared Iraqi President Saddam Hussein a menace "and we're going to deal with him."

He said Saddam has a record of killing his own people, developing weapons of mass destruction and breaking an agreement to allow weapons inspectors into the country.

Asked if Hussein was still holding a U.S. pilot captured in the Persian Gulf War, the president replied, "Wouldn't put it past him."

But despite his tough talk, and the fact that American troops are even now scouring Afghanistan caves for Al Qaeda and Taliban warriors, Bush played down the importance of capturing or killing Usama bin Laden.

"Deep in my heart I know the man's on the run — if he's alive at all," he said. "Who knows if he's hiding in some cave or not? We haven't heard from him in a long time. The idea of focusing on one person really indicates to me that people don't understand the scope of the mission. Terrorism is bigger than one person and he's a person who's now been marginalized.

"I don't know where he is. I just don't spend that much time on it. ... I can assure you I am not going to blink."

By turns, Bush flashed anger and humor as he fielded questions on more than a dozen topics.

He said he could "barely get my coffee down" when he read of the Immigration and Naturalization Service's belated dispatch of student visa approvals for two of the terrorists who slammed hijacked jets into the World Trade Center on Sept. 11.

"I was stunned and not happy. ... I was plenty hot," he said. 

On the Middle East, where attacks and retaliation have increased, Bush offered his most direct criticism yet of Prime Minister Ariel Sharon's tough crackdown on Palestinians.

"Frankly, it is not helpful what the Israelis have recently done," Bush said. "I understand somebody trying to defend themselves ... but the recent actions are not helpful."

He urged both Israelis and Palestinians to "work hard to create conditions for a potential settlement" when U.S. mediator Anthony Zinni returns to the region on Thursday.

Bush, who travels to Moscow in May for another round of talks with Russian President Vladimir Putin, said he would go along with Russian demands for a written agreement to codify expected arms reductions. Bush said he now agrees with Putin "that there needs to be a document that outlives both of us."

The president defended his administration's refusal to give congressional investigators records of Cheney's energy task force consultations with energy company executives who contributed to the Bush campaign — including embattled Enron officials.

"I'm not going to let Congress erode the power of the executive branch. We're not going to give them to 'em. These are privileged conversations," Bush said.

On a day when he spent several hours with Irish and Irish-American leaders celebrating an early St. Patrick's holiday, Bush was asked about the sex-abuse scandal within the Roman Catholic Church in Boston.

"I know many in the hierarchy in the Catholic Church. I know them to be men of decency. ... I'm confident the church will clean up its business," he said.

The Associated Press contributed to this report.