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Celebrities mobilized against a possible war in Iraq on Tuesday, gathering to publicize a letter urging President Bush to avoid military action.

More than 100 entertainers signed the missive, which says a war with Iraq will "increase the likelihood of terrorist attacks, damage the economy and undermine our moral standing in the world."

"This notion of pre-emptive war is setting a precedent ... and we must ask ourselves, where does this end?" said Tony Shalhoub, star of the ABC detective show Monk. "Where is the next pre-emptive strike?"

Shalhoub, Martin Sheen and Mike Farrell were among nearly a dozen performers who got together to draw attention to their cause.

Farrell, who's co-starred in the television series M*A*S*H and Providence, said Hollywood was speaking out to show average citizens that it's OK to voice dissent. He also said he did not believe that Bush has proven Iraq is a danger to America.

"It is inappropriate for the administration to trump up a case in which we are ballyhooed into war," Farrell said.

Among those signing the letter were Academy Award winners Kim Basinger, Helen Hunt, Olympia Dukakis, Susan Sarandon and director Jonathan Demme.

Other names included former X-Files stars Gillian Anderson and David Duchovny; The West Wing cast members Sheen, Janel Moloney, Bradley Whitford and Lily Tomlin; CSI: Crime Scene Investigation actors Marg Helgenberger and Robert David Hall; and Ocean's Eleven co-stars Matt Damon, Don Cheadle, Elliott Gould and Carl Reiner.

R.E.M.'s Michael Stipe, Peter Buck and Mike Mills joined fellow musicians Peter Yarrow and Bonnie Raitt.

Bush has threatened military force against Saddam, saying the dictator has amassed weapons of mass destruction that pose a danger to the United States. U.N. weapons inspectors are searching the Middle Eastern country for such devices but have turned up little so far.

Sheen, who plays the president on The West Wing, said he believed Bush was eager to go to war with Iraq because he wanted to settle a personal score with Saddam Hussein.

When Bush's father was president, he ended Saddam's invasion of Kuwait but did not eliminate him in the Gulf War.

"I think he'd like to hand his father Saddam Hussein's head and win his approval for what happened after the Gulf War. That's my own personal opinion — I don't know if that's true. I hope it's not, but I suspect it is," Sheen said.

Asked why the government should care about the feelings of Hollywood actors, Sheen said: "I think the president should care about all citizens."