THE United Nations faces a daunting range of challenges in the 21st century: promoting development without fostering dependency; combating climate change without reducing growth; defending human rights without insisting on one true path. But in the past five years, a specter has risen, casting a shadow across the world: the specter of extremism, instability and injustice gripping the Middle East.

The United Nations needs new leadership that understands these issues and can address all sides with experience and credibility. The fight against extremism is necessarily one with winners and losers ? one where compromise may equal defeat and where genocide, mass murder and terrorism loom. The leadership of the United Nations must take a stand. To me, there is no starker lesson from the United Nations? failures in Bosnia and Rwanda.

The recent outbreak of war (and fragile peace) in Lebanon, and the conflicts in Africa, have reminded the world of the United Nations? unique legitimacy in restoring peace and security. Global legitimacy on its own, however, is not enough. The United Nations must also be effective. It should draw on the remarkable success of those societies ? not least in Asia ? that have seized on the promise of globalization to renew themselves. Like them, the United Nations must have the courage to discard the old and embrace the new in the name of progress.

The struggle against extremism and intolerance requires the efforts of every society, faith and agent of human dignity. The United Nations must recognize this struggle for what it is and be willing to play its vital part. Only if the United Nations has the will to change itself can it change the world.

? ZEID RAAD ZEID AL-HUSSEIN, Jordan?s ambassador to the United Nations, a former peacekeeper in the Balkans and the first president of the governing body of the International Criminal Court.