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The nations of the world joined Monday in solemn remembrance of Sept. 11 attacks, with allies in the U.S.-led war on terrorism renewing their resolve to fight fanaticism but militants blasting Washington's response as ineffective and pledging continued resistance.

As heads bowed in moments of silence for the 3,000 killed in the attacks on New York and Washington, a top Al Qaeda leader issued new warnings in a videotape. And dissident voices brushed the portrait of a planet that has traded in civil liberties and other democratic rights in its war on terror.

The outpouring of emotion reflects an international landscape vastly changed since terrorists hijacked four airliners in 2001, crashing two into New York's World Trade Center, one into the Pentagon and another into a Pennsylvania field.

Get complete coverage of the fifth anniversary of 9/11 in FOXNews.com's special Sept. 11 Center.

In a video broadcast Monday, Al Qaeda No. 2 Ayman al-Zawahiri warned that Persian Gulf countries and Israel would be Al Qaeda's next targets and he called on Muslims to step up their resistance against the United States. He accused the governments of Egypt, Jordan and Saudi Arabia of supporting Israel's war against Hezbollah in Lebanon.

Another video posted on the Internet, purportedly by Al Qaeda, showed previously unseen footage of a smiling bin Laden and other commanders in a mountain camp apparently planning the Sept. 11 attacks.

New Zealand's Prime Minister Helen Clark joined many when she said: "No, we're not more secure since 9/11."

Clark said more should be done to reach out to moderate states and leaders in the Islamic world to encourage understanding between different peoples, and to help end the sense of alienation and exclusion among some young Muslims that fuels extremism.

In Europe, struck by terrorist attacks three times since Sept. 11, commemorations touched each nation.

Bells tolled in Rome's city hall square.

"9/11 will be in our memory forever," said Rome Mayor Walter Veltroni during a ceremony in the a downtown piazza designed by Michelangelo. "We all remember where we were, what we were doing, what our first reaction was.

Photo Essay: Attack on the World Trade Center

In London, bouquets of white roses and yellow carnations were piled in a memorial garden where the names of 67 Britons killed in the New York attacks are inscribed — and where a steel girder from the wreckage of the World Trade Center is buried. Relatives tearfully remembered their dead.

"It doesn't get any easier, but our minds are much calmer, and we can think through all the events without being flooded by tears and sadness," said Adrian Bennett, 55, whose 29-year-old son, Oliver, was among the victims.

At a 38-nation Asia-Europe summit in Helsinki, Finland, leaders stood in silence in a circle. The stock exchanges in Nordic and Baltic countries were observing two minutes of silence to honor the victims of the world's worst terror attacks.

Photo Essay: Attack on the Pentagon

France's President Jacques Chirac, in Helsinki, reiterated in a written message to President Bush his nation's "friendship" in the fight against terrorism.

A week after the Sept. 11 attacks, Chirac flew over the World Trade Center site — the first foreign leader to pay personal condolences. That solidarity quickly dissipated into rancor in the buildup to the Iraq war, when Chirac led opposition to Bush's plans.

Israel's Haaretz daily expressed disappointment and cynicism in an op-ed piece that said: "This is Sept. 11 five years later: a political tool in the hands of the Bush administration."

Photo Essay: Flight 93 Crashes in Shanksville, Pa.

Even German Chancellor Angela Merkel — an advocate of closer ties with Washington — had veiled criticism of the United States, saying: "The ends cannot justify the means."

"In the fight against international terror ... respect for human rights, tolerance and respect for other cultures must be the maxim of our actions, along with decisiveness and international cooperation," she said.

In Southeast Asia, U.S. and Philippine troops fighting Islamic extremists in the jungles prayed for peace and safety, as other remembrances took place in Japan, Australia, Finland, South Korea, Thailand and Indonesia.

Photo Essay: The World Mourns for Victims of Sept. 11

Afghan President Hamid Karzai, who won the country's first post-Taliban election in 2004, expressed the appreciation of the Afghan people to the U.S. for the "sacrifices of your sons and daughters" in rebuilding his country. But on the streets in the capital, Kabul, many Afghans grumbled that they had not seen much improvement.

Despite about 20,000 U.S. forces fighting Al Qaeda and Taliban fighters in Afghanistan, and about the same number of NATO troops, and billions in aid, a resurgent Taliban resistance has shaken the country, while corruption has stymied development.

Photo Essay: America Rebuilds After the Worst Terror Attacks in U.S. History

NATO Secretary General Jaap de Hoop Scheffer led a solemn military ceremony outside the alliance's headquarters to remember the victims. A lone bugler played "Taps" while a ceremonial guard, drawn from each of the 26 NATO member nations, lowered national flags to half-staff in tribute before those gathered outside observed a minute of silence.

"Terrorism remains a threat to all of us ... this is why we are in Afghanistan, the cradle of 9/11," de Hoop Scheffer said, calling on NATO nations to "strengthen our alliance politically and militarily to meet this new scourge."

In Pakistan, considered a major ally in the U.S.-led war on terror, newspapers ran bleak-toned opinion columns and editorials criticizing Western anti-terror policies and attitudes.

Complete coverage of the anniversary of 9/11 is available in FOXNews.com's special Sept. 11 Center.