WASHINGTON -- Outwardly, President Bush gives every indication that public opinion will play no role in his imminent decision on whether to go to war against Iraq.

After a recent weekend of huge protest rallies around the world, Bush observed that worrying about anti-war sentiment would be like formulating policy "based upon a focus group. The role of the leader," he said, "is to decide policy based upon the security ... of the people."

The president forcefully reiterated that view at his press conference last week. "I appreciate societies in which people can express their opinion," he said, but then added: "My most important job is to protect the security of the American people. That's precisely what I'll do."

And so, despite some of the most vehement anti-war demonstrations since the Vietnam War, Bush appears ready to order a military attack on Iraq -- persuaded, he says, that to ignore Saddam Hussein's weapons would be to gamble with American lives.

"I don't run my administration based upon polls and focus groups," said Bush. "I'm running this war against terror based upon freedom."

Yet public opinion, in many respects, is at the heart of the global fight about Iraq, and it's likely to stay there.

By all accounts, overwhelming public opposition in Europe is the reason Bush decided to take his case to the United Nations in the first place, where he now faces a showdown vote over his plea for international support.

Even stronger anti-war sentiment in Turkey has prompted the new government there to rebuff tremendous pressure from the United States to allow tens of thousands of troops to mass on the Iraq border.

And, should Bush make the decision to attack, military experts say that popular reaction in the Middle East to a U.S.-instigated war, and to a continuing American presence in the country, would be crucial factors in judging whether the president was correct in arguing for war.

"Although the White House likes to say they don't read polls, public opinion is having a powerful effect in many ways," said Carroll Doherty, editor of the Pew Research Center, which recently completed a worldwide survey of public opinion.

In the run-up to what appears to be a likely confrontation in Iraq, the spotlight has been on Americans' views as they judge the wisdom of an Iraq invasion. Would the anti-war movement gain ground? Would Bush retain majority support for a military campaign?

But policymakers say the public opinion focus would instantly go global when the first wave of bombs started falling on Baghdad, attention then falling to the reactions of the Iraqis and other Arabs in the region.

Would the Iraqi people greet American GIs as liberators, or as infidels? Would a longer-term presence of U.S. troops in Iraq bring stability to the region or inflame already strong anti-American views? Would support for terrorism wane as a result of the war, or grow?

With American military officials offering guarantees that the outcome of an Iraqi war is not really in doubt, the answers to these questions may emerge as the ultimate measures of American success in Iraq.

And in this regard -- the battle for the hearts and minds of Middle East Arabs -- Bush has his work cut out, says Anthony Cordesman, a military scholar at the Center for Strategic and International Studies, a foreign policy think tank in Washington.

"We need to understand just how deeply hostile the Arab world is," said Cordesman. "We may or may not be perceived as liberators."

American officials must recognize that postwar U.S. initiatives in the region will be subject to unprecedented public scrutiny throughout the Mideast, Cordesman said. "Everything we do from bombing to the first ground contact with Iraqis will be conducted in a media fishbowl," he said.

Many foreign policy experts are dubious, at best, about whether the United States can occupy Iraq without inflaming anti-American passion.

Retired Gen. Wesley Clark says the Arab world will see the United States as a "colonial" invader following in the tradition of the British and the Ottomans.

Former U.N. weapons inspector David Kay says the administration faces daunting odds.

"It's going to be extremely difficult," he said. "I think they have benefited from seeing what happened in Bosnia, what happened in Kosovo, what's happening in Afghanistan. ... We'll see if they get it right this time.

"They better," he said. "The stakes are a lot higher."