We can't say whether Tehran is supporting Al Qaeda, but we do know that al-Qaida people come here from Pakistan through Iran.

I consider the modernization of the Middle East the central challenge of our time. This region behaves as if it were disturbed, if you'll excuse the clinical expression.

During the Cold War era, the issue was the containment of Soviet influence, and we tolerated many an authoritarian regime as long as they were useful to us in this respect.

The Sunnis continue to see themselves, possibly for nostalgic reasons, as the most influential group and want a stronger central government - quite unlike minorities in other countries. The circumstances here are far more complex than many people in Washington imagine.

Nation building is our central task, both in Afghanistan and in Iraq. And states, nations can't just be built with military power. Despite all difficulties, it's very inspiring to see how the Kurds, the Arab Sunnis and the Shiites are coming together here, how they're jointly defining the basis on which their state is to be built, the political course this state will pursue and who is to receive which cabinet positions.

Americans have eliminated Iran's worst enemies, the Taliban in Afghanistan and Saddam [Hussein]. I occasionally threatened my Iranian counterpart in Kabul that one day I would send him a big bill for what we did. But, seriously, Iran is pursuing a dual strategy in Iraq. On the one hand, the Iranians, after decades of hostility, are now interested in good relations. On the other hand, they want to keep the country weak and dominate the region.

Success in Iraq will be a major setback for terrorists and a major asset for the security of this region. The struggle for Iraq is the struggle for the future of the world.