President Bush, reaching out to an audience he has antagonized in the past, told the assembled leaders of the world Wednesday that the United States shared "a moral duty" to combat not only terrorism but also the poverty, oppression and hopelessness that give rise to it.

Addressing the United Nations, Bush linked his campaign against terrorism to the anti-poverty agenda advanced by other nations, although he shied away from adopting some of the specific commitments sought by allies. He later took the U.S. seat at the Security Council for the first time in his presidency to emphasize his solidarity with other countries in the struggle against terrorism.

"We must help raise up the failing states and stagnant societies that provide fertile ground for the terrorists," Bush said at the gathering of more than 150 presidents and prime ministers on hand to mark the 60th anniversary of the world body. "We must defend and extend a vision of human dignity and opportunity and prosperity, a vision far stronger than the dark appeal of resentment and murder. To spread the vision of hope, the United States is determined to help nations that are struggling with poverty."

Arguing that trade can lift hundreds of millions of people out of poverty, Bush pushed for a new global trade agreement and for the first time vowed to drop all U.S. tariffs, subsidies and other barriers to foreign goods if other countries do the same. He also urged other nations to join U.S. efforts to fight AIDS and malaria, and he launched a new international partnership to address the spread of avian flu.

Paying special notice to perennial conflicts that leave much of the world destitute, Bush said the United States would train 40,000 African peacekeeping troops over five years "to preserve justice and order in Africa." And he marked the inception of a new U.N. democracy fund to promote greater liberty around the world.

"The lesson is clear," Bush said. "There can be no safety in looking away or seeking the quiet life by ignoring the hardship and oppression of others. Either hope will spread or violence will spread, and we must take the side of hope."

On the sideline of the U.N. events here, Bush also met for 35 minutes with Israeli Prime Minister Ariel Sharon to congratulate him on the withdrawal from the Gaza Strip and to challenge the Palestinians to reciprocate. "I know it was hard, but I admire your courage," Bush told Sharon in front of reporters. The president added: "Now is the time for Palestinians to come together and establish a government that will be peaceful with Israel."

Bush's two-day visit here focused his attention back on world affairs at a time of domestic crisis along the Gulf Coast. Many of his counterparts expressed their sympathy following the death and devastation caused by Hurricane Katrina; more than 115 countries have offered assistance. Comparing Katrina to the tsunami that killed hundreds of thousands in South Asia last year, Bush said the outpouring of compassion this month showed that the world is better "when we act together."

The rhetorical nod to international harmony contrasted with past visits by Bush to the United Nations that were marked by bitter disagreement over the war in Iraq. Since his reelection last year, Bush has worked to heal those wounds and has adopted a more multilateral approach to sensitive issues such as Iran's nuclear program.

His approach Wednesday generated a far warmer reaction among U.N. officials and foreign delegates than previous appearances, when he lectured countries about their responsibility to fight terrorism and stand up to North Korea and Iraq. Diplomats praised Bush's embrace of targets known as the Millennium Development Goals to dramatically scale back poverty, child mortality and disease, although he did not endorse proposals to spend 0.7 percent of national income on international aid, four times more than current U.S. spending.

"It was a different tone," said Chile's ambassador, Heraldo Munoz. "Before, it was all about terrorism. Although this speech had an unavoidable component on terrorism, it went well beyond. He expressed . . . renewed trust in the United Nations, and I feel many leaders welcomed that."

At the same time, Bush was trailed around U.N. headquarters by his ambassador, John R. Bolton, a longtime U.N. critic who was sent here with a temporary recess appointment after Senate Democrats blocked his confirmation. Bolton has clashed with diplomats here over efforts to make the United Nations more efficient and accountable.

When Bush was greeted by Secretary General Kofi Annan on Tuesday, U.N. closed-circuit television showed the president joking about the tension over Bolton, who once suggested it would make no difference if 10 floors of the U.N. building disappeared. "How is he behaving?" Bush asked. "Has the place blown up?"

A 35-page declaration on poverty and U.N. reform completed this week did little to overhaul the organization in the way Washington wants, but Bush publicly credited Annan for trying. "We have made a solid start," he said in a toast. "More work remains."

U.N. officials sought to counter the impression that weeks of hard negotiations had yielded a scaled-back document that would have little impact. The declaration, to be endorsed by world leaders attending a summit on Friday, includes the first unqualified U.N. condemnation of terrorism "by whomever, wherever and for whatever purpose." It also constitutes the first public commitment by the full U.N. membership to take responsibility for protecting people from genocide, war crimes, ethnic cleansing and crimes against humanity. The declaration does not legally obligate governments to intervene in places such as the Darfur region of Sudan, but it will increase political pressure on countries to do so.

As it has during many of Bush's visits here, terrorism dominated the agenda, coming on a day when more than 160 people were killed and hundreds more injured by a wave of bombings and rocket attacks in Baghdad. Many of the leaders sitting with Bush at the Security Council, including Russian President Vladimir Putin and Chinese President Hu Jintao, did not support the U.S. invasion of Iraq.

But they agreed with Bush and British Prime Minister Tony Blair to adopt the resolution calling on nations to crack down on the incitement of terrorism.

"The terrorists must know that wherever they go they cannot escape justice," Bush said, adding, "We must send a clear message to the rulers of outlaw regimes that sponsor terror and pursue weapons of mass murder: You will not be allowed to threaten the peace and stability of the world."

President Bush attends a Security Council meeting.