President Bush defended the U.S. and British mission in Iraq Wednesday, saying the two global democracies had a responsibility to see the mission through and to quash terrorism where it thrives.
"The evil is in plain sight," Bush said in an address at Whitehall Palace (search) in London. "The danger only increases with denial. Great responsibilities fall once again to the great democracies. We will face these threats with open eyes and we will defeat them."
Bush's speech focused on his "three pillars" for peace and security: that international organizations must be equal in facing the challenges of the word and live up to the policy of multilateralism the Allies have carried out since World War II; to retain aggression and evil by force when necessary; and for countries committed to democracy to help fight terror and spread democratic values.
He also vowed that the United States will not retreat from democratization efforts in Iraq or other countries because of "a band of thugs and assassins," despite the fact that coalition troops in Iraq come under daily attack by fighters.
"The violence we are seeing in Iraq today is serious ... it is the nature of terrorism and the cruelty of a few to try to bring grief and a loss to many."
Bush kicked off a long day of speeches, formal meals and likely anti-war protests with the address, in which he said that the war in Iraq was a necessary use of military power.
"On Sept. 11, 2001, terrorists left their mark of murder on my country and took the lives of 67 British citizens," Bush said. A total of about 3,000 people were killed on Sept. 11.
Bush stressed that the terror attacks "were not dreams -- they're part of a global campaign by a terrorist network to demoralize all who oppose them. These terrorists target the innocent and they kill by the thousands."
But if the terrorists gain the weapons of mass destruction they seek, the president added, "they would kill by the millions."
'We Will Use Force When Necessary'
Britain and its prime minister, Tony Blair (search), have been Bush's staunchest allies in the war in Iraq. Bush credited Blair for his diplomatic attempts at the United Nations and for standing by his decision to send British troops into battle.
"The United States and Great Britain share a mission beyond the balance of power or the simple pursuit of interest," Bush said. "We seek the advance of freedom and the peace that freedom brings. Together our nations are standing and sacrificing for this high goal in a distant land at this very honor. And American honors the idealism and the bravery of the sons and daughters of Britain."
He said that in some cases, the measured use of force "is all that protects us from a chaotic world ruled by force" and "our great democracies should oppose tyranny wherever it is found."
"We will use force when necessary to defend the ideals of freedom."
Of the Middle East, Bush said, "we will consistently challenge the enemies of reform" and "we will meet our responsibilities in" in Afghanistan and Iraq.
Bush didn't ignore the fact that there were "good-faith disagreements" in the United States and Britain, among other countries, on the timing of the war and how to go about it. But "whatever has come before, we now have only two options: to keep our word or to break our word," he said.
"The failure of democracy in Iraq will throw itself back to misery and turn that country back to terrorists that wish to destroy us. Yet democracy will succeed in Iraq because our will is firm, our word is good and the Iraqi people will not surrender their freedom."
Bush tried to puncture what he views as misconceptions on this side of the Atlantic about America's use of force. He invoked Europe's history of appeasement of dictators, and the price Europeans paid for their governments' inaction.
He reminded Europeans about the critical work the Allies did to set postwar Germany on the path to democracy, a process the Bush administration and the British are trying to accelerate today in Iraq.
"Let us never forget how Europe's unity was achieved," Bush said. "Together our nations are standing and sacrificing ... in a distant land at this very hour."
In a friendly jab at France, Bush noted how a 14-point plan for peace following World War I that President Woodrow Wilson took to Britain in 1918 was met with skepticism by the prime minister of France, who complained then that even God himself "only had 10 commandments."
"Sounds familiar," he said, referring to Prime Minister Jacques Chirac's staunch opposition of the U.S.-led war in Iraq.
Of reconstruction in Iraq, Bush said, "this is substantial progress and much of it has succeeded faster that previous efforts in Germany and Japan in World War II."
Blair also defended Britain's close relationship with the United States and the coalition's handling of the situation in Iraq.
"It really is about time we started to realize who our allies are, who our enemies are, stick with the one and fight the other," Blair told the House of Commons, to loud cheers.
Protesters Flock to London
The palace was also a focal point for demonstrators bitterly opposed to the Iraq war.
They shouted "Murderer!" and "You are not welcome!" as Bush's helicopter ferried him to the palace Tuesday night. Wednesday morning, they gathered again behind metal barriers, watched by large numbers of yellow-jacketed police officers.
But Bush took it all in stride, filling his speech with lighthearted jokes about the protests. He noted that protesters were vigorously exercising their right to free speech and said, "they now have that right in Baghdad as well."
Bush noted that the last American to cause such a ruckus in the city was illusionist David Blaine (search), who recently spent 44 days in a self-imposed fast in an elevated plastic box above the Thames River. For the first few days, Blaine's box was pelted with food and the people jeered at him.
"A few might have been happy to provide similar arrangements for me," Bush said, adding that he was grateful to the Queen for interceding and allowing him to stay at Buckingham Palace (search).
Britain has sent more troops to Iraq than any country aside from America, about 9,000, and the British have lost more than any other American ally -- 52 deaths since the start of the war. Bush was to sit down with family members of British soldiers killed in Iraq on Thursday.
"The British people are the sort of partners you want when serious work needs doing," Bush said. "America is fortunate to call this country our closest friend in the world."
Fox News' Liza Porteus and The Associated Press contributed to this report.