"Many of these folks are sincere and they're patriotic, but they could not be more wrong," Mr. Bush told an audience of thousands of veterans at the American Legion convention in Salt Lake City.
The consequences of pulling out before the mission in Iraq is completed, Mr. Bush said, "would be absolutely predictable and absolutely disastrous. We would be handing Iraq over to our worst enemies – Saddam's former henchmen, armed groups with ties to Iran, and al Qaeda terrorists from all over the world who would suddenly have a base of operations far more valuable than Afghanistan under the Taliban."
In the first of a series of speeches in defense of staying the course in Iraq, Mr. Bush said the U.S. will not leave until victory is achieved.
"The war we fight today is more than a military conflict," Mr. Bush said. "It is the decisive ideological struggle of the 21st century."
Mr. Bush chose a friendly audience in a conservative state to begin a pre-election series of speeches touting his war strategy. The three-week campaign is centered on the fifth anniversary of the Sept. 11 terror attacks.
The president described the current violence in the Middle East and the recently thwarted attack to blow up planes over the Atlantic Ocean as part of the same movement that resulted in the Sept. 11 attacks. He likened the struggle against Islamic fundamentalism with the fight against Nazis and communists.
"As veterans you have seen this kind of enemy before," Mr. Bush said. "They are successors to fascists, to Nazis, to communists and other totalitarians of the 20th century. And history shows what the outcome will be.
"This war will be difficult. This war will be long. And this war will end in the defeat of the terrorists," Mr. Bush said.
Mr. Bush acknowledged the unsettling times, marked by sectarian violence in Iraq, disputes along the Israel-Lebanon border and terrorists allegedly plotting to blow up planes between Britain and the United States.
"The images that come back from the front lines are striking and sometimes unsettling," he said. "When you see innocent civilians ripped apart by suicide bombs or families buried inside their homes, the world can seem engulfed in purposeless violence."
Mr. Bush said those who were responsible for bringing down the World Trade Center are united with car bombers in Baghdad, Hezbollah militants who shoot rockets into Israel and terrorists who wanted to bring down the flights between Britain and the United States.
"Despite their differences these groups form the outline of a single movement, a worldwide network of radicals that use terror to kill those who stand in the way of their totalitarian ideology," Mr. Bush said. "And the unifying feature of this movement, the link that spans sectarian divisions and local grievances, is the rigid conviction that free societies are a threat to their twisted view of Islam."
Mr. Bush also delivered his starkest threat yet to Iran its defiance and delay to demands to stop enriching uranium.
"There must be consequences for Iran's defiance,'' he said, "and we must not allow Iran to develop a nuclear weapon."
Thursday was the deadline for Tehran to heed the U.N. Security Council demand to stop enrichment.
"The world now faces a grave threat from the radical regime in Iran,'' the president said. ``We know the depth of suffering that Iran's sponsorship of terrorists has brought. And we can imagine how much worse it would be if Iran were allowed to acquire nuclear weapons."
It is the third time in less than a year that Mr. Bush has made a series of speeches on Iraq and terrorism. The speeches come two months before congressional elections and at a time when his when many Americans are disillusioned with his strategy.
Mr. Bush insisted, however, that the speeches were not politically motivated.
"They are not political speeches," Mr. Bush said Wednesday in Little Rock, Ark., where he made a campaign stop with Asa Hutchinson, a former congressman who is running for governor against Democrat Mike Beebe.
"They're speeches about the future of this country and they're speeches to make it clear that if we retreat before the job is done, this nation will become even more in jeopardy."
But even in Utah – which gave Mr. Bush a wider margin of victory than any other state in the 2004 election – the president's appearance was a source of dispute. Salt Lake City Mayor Rocky Anderson, a Democrat, led thousands of anti-Bush demonstrators on a march through the city Wednesday. He called Mr. Bush a "dishonest, warmongering, human-rights-violating president."
The White House countered by organizing a campaign-like rally at the airport for Mr. Bush's arrival Wednesday night. A couple thousand cheering supporters, who got tickets from the governor's office and the congressional delegation, stood under flood lights and cheered as Mr. Bush pledged to stay in Iraq.
While in Salt Lake City, Mr. Bush had a half-hour private meeting with leaders of the Church of Jesus Christ of Latter-day Saints. He also spoke at a luncheon fundraiser for Republican Sen. Orrin Hatch.