U.S. Secretary of State Hillary Clinton says the world needs to band together to thwart extremists trying to undermine the advance of democracy in the strife-torn countries of North Africa and the Middle East.

Clinton spoke in New York at the Clinton Global Initiative, the annual forum on world affairs led by her husband, former U.S. President Bill Clinton.

“All of us need to stand together to resist these forces and to support democratic transitions underway in North Africa and the Middle East.”

She said unity among world leaders in the fight against terrorism is crucial “because extremists around the world are working hard to drive us apart.” Clinton said countries that are focused on developing their economies and governmental institutions rather than “fomenting grievance” are advancing in the world community.

Clinton said the democracy movements that have sprung up throughout the world “create exciting possibilities for countries that have been ruled for years by dictators.” But she said countries facing change have to determine how they can best “turn their democratic ideals into functioning governments and prosperous economies.”

The chief American diplomat is in New York meeting with several world leaders as they arrive for the annual United Nations General Assembly. U.S. President Barack Obama is set to speak Tuesday at the U.N., as are other world leaders in the next several days.

United Nations Secretary-General Ban Ki-moon says Syria will be on top of every leader's mind as the General Assembly session opens.

More than 120 world leaders will attend the meeting to discuss and debate wars, political crises and humanitarian concerns. The major meetings get under way Tuesday.

The world is deadlocked on how to deal with the civil war in Syria, which has killed more than 20,000 people, mostly civilians. Russia and China have vetoed tough sanctions against the Syrian government in the Security Council, and the United States has expressed no desire for military intervention.

Other major issues expected to dominate the General Assembly include tensions between Israel and Iran, and the deadly protests in the Middle East over the anti-Muslim film made in the United States.