UNITED NATIONS — President Bush, who once expressed disdain for the United Nations, said Tuesday that multinational organizations are now "needed more urgently than ever" to combat terrorists and extremists who are threatening world order.

In his eighth and final speech to the U.N. General Assembly, Bush said the international community must stand firm against the nuclear ambitions of North Korea and Iran. He said that despite past disagreements over the U.S.-led war in Iraq, members of the U.N. must unite to help the struggling democracy succeed. And he scolded Russia for invading neighboring Georgia, calling it a violation of the U.N. charter.

"The United Nations' charter sets forth the equal rights of nations large and small," he said. "Russia's invasion of Georgia was a violation of those words."

Bush called on the international community to rally behind young democracies like Georgia.

"Democracies around the world are watching to see how we respond to this test," Bush said. "The United States has worked with allies in multilateral institutions, like the European Union and NATO, to uphold Georgia's territorial integrity and provide humanitarian relief. ... In this chamber are representatives of Georgia, and Ukraine, and Lebanon, and Afghanistan, and Liberia, and Iraq, and other brave, young democracies. We admire your courage. We honor your sacrifices. We thank you for your inspiring example."

Bush said that instead of issuing statements and resolutions after terrorist attacks, the U.N. and such organizations must work closely to prevent violence. Every nation has responsibilities to prevent its territory from being used for terrorist, drug trafficking and nuclear proliferation, he said.

Bush, who ordered the U.S.-led invasion of Iraq without the U.N.'s blessing, said: "The United Nations and other multilateral organizations are needed more urgently than ever."

His appearance was overshadowed by the U.S. financial markets crisis that has rippled through world markets. Trying to reassure world leaders that his administration is taking decisive action to stem market turmoil, Bush said he is confident that Congress will act in the "urgent time frame required" to prevent broader problem. But he did not ask other nations to take any specific actions.

The president worked to strike a hopeful tone about the war on terrorism, insisting that while regimes like Syria and Iran continue to sponsor terror, "their numbers are growing fewer, and they're growing more isolated from the world." He called on the U.N. membership to stand united against terrorism and tyranny.

"As the 21st century unfolds, some may be tempted to assume that the threat has receded," Bush said. "This would be comforting. It would be wrong. The terrorists believe time is on their side, so they've made waiting out civilized nations part of their strategy. We must not allow them to succeed."