Washington ? On the six-month anniversary of the Sept. 11 terrorist attacks, President Bush called on nations around the world Monday to join the second phase of the war on terrorism, vowing to pursue and destroy “terrorist parasites” wherever they hide.

Flanked by ambassadors from more than 100 countries, Bush marked the six-month milestone by renewing his commitment to a relentless global war against terrorists and their allies. He prodded other governments to join the fight and promised U.S. aid to any willing partner.

President Bush walks through an honor guard as he prepares to address more than 1,000 people gathered at the White House. Ambassadors, members of Congress, relatives of some 300 victims and top administration officials attended ceremonies Monday marking six months since the terrorist attacks on the Pentagon and the World Trade Center in New York.

In the clearest statement yet of his phase-two war strategy, Bush said the United States would rely on other nations to root out homegrown terrorists, but would lead efforts to prevent terrorists from obtaining nuclear, chemical or biological weapons.

“There is no margin for error, and no chance to learn from mistakes. Our coalition must act deliberately, but inaction is not an option,” he said. “Men with no respect for life must never be allowed to control the ultimate weapons of death.”

Bush outlined his plan for the war’s expansion at a solemn ceremony on the White House’s south lawn. His audience included about 300 relatives of the Sept. 11 victims, members of Congress, Supreme Court justices and most of Washington’s foreign diplomatic corps.

Flags from more than 150 countries flapped in the crisp breeze under a blue sky that stirred memories of the beautiful late-summer morning that was shattered by tragedy six months ago. As he spoke, jets from nearby Ronald Reagan Washington National Airport occasionally roared overhead while wary Secret Service agents scanned the skies from the roof of the White House.

International remembrance

The White House ceremony was part of an international day of remembrance for the Sept. 11 victims.

In New York, a crowd near the flattened World Trade Center fell silent at 8:46 a.m. and again at 9:03 a.m. to mark the moments when two hijacked planes slammed into the twin towers. At the Pentagon, another Sept. 11 target, Defense Secretary Donald H. Rumsfeld mourned the victims with representatives from 29 countries that have joined the anti-terrorism campaign in Afghanistan.

In London, British Prime Minister Tony Blair welcomed Vice President Dick Cheney at a ceremony at Blair’s official residence, Number 10 Downing Street.

With the Capitol in the background, center, construction work continues on the Pentagon. Six months after the Sept. 11 attacks, the Pentagon's restoration work is more than half finished.

And in Afghanistan, U.S. troops fought the hard-core remnants of Osama bin Laden’s al-Qaida forces. Meanwhile, the second phase of the war is beginning to unfold in the Philippines, Yemen and the former Soviet republic of Georgia. In all three countries, American military officials will help train local forces to combat terrorists.

Day of decision

Echoing Franklin Roosevelt’s declaration that Dec. 7, 1941, was “a date which will live in infamy,” Bush said Sept. 11, 2001, would be remembered as “a day of decision, when the civilized world was stirred to anger and action” against terrorists.

He said that terrorists would remember Sept. 11 as “the day their reckoning began.”

The president, who once vowed to take bin Laden “dead or alive,” never mentioned the terrorist leader in his glowing assessment of the war’s progress.

The U.S.Postal Service has a hero stamp that will be issued in late spring. The stamp unveiled Monday uses the famous Sept. 11, 2001, photo of firefighters, from left, George Johnson, Dan McWilliams and Billy Eisengrein raising the American flag at the World Trade Center disaster site in New York.

Although the American-led coalition ousted Afghanistan’s hard-line Islamic Taliban regime, which had been harboring bin Laden and al-Qaida forces, he and other top al-Qaida leaders have eluded capture.

Bush counseled patience and suggested that the hunt for bin Laden and his lieutenants is far from over.

“For terrorists fleeing Afghanistan for any terrorist looking for a base of operations there must be no refuge, no safe haven,” he said.

“Every terrorist must be made to live as an international fugitive, with no place to settle or organize, no place to hide, no governments to hide behind and not even a safe place to sleep.”

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