SAN FRANCISCO: Tuesday morning's attacks on the people of New York and Washington, DC are a stunning demonstration of humanity's capability to reduce the best of what we are to rubble, smoke, and death.

In the aftermath of such horror, it is natural for Americans to want to retreat from the rest of the world. It is normal and right to draw close to loved ones and to stay at home, denying entry to the strange, the dangerous, the frightening. Our anger will be profound.

Our love and hope must be equally profound. May we, the living, find the wisdom and courage to bring about a world of greater justice for the disenfranchised while ensuring safety for all. In the days, weeks, and months ahead, Americans must join the rest of the world in seeking common solutions so that such tragedies, born of hatred and fear, do not occur again.

The United States will be navigating a minefield as we seek to craft a response that is effective and forceful while still in keeping with our national values - a response that demonstrates that Tuesday's attacks were intolerable but does not further stoke the flames of hate and resentment abroad. Our duty is to ensure that desperation does not lead to even greater irrational destruction.

Without diminishing the magnitude of this tragedy, we would be remiss not to acknowledge that the horror could have been much greater. We must think the unthinkable: what would have happened to New York and Washington had nuclear weapons been used?

The proliferation of weapons of mass destruction-and particularly of nuclear weapons-would create the potential for even more horrific attacks in the future. We have long known the steps necessary to stem the spread of nuclear, chemical and biological weapons, but have lacked the political resolve to carry them out. As we grieve and express our anger, we must also find the strength to turn this tragedy into a call to ensure that terror of this scale can never occur again.

First, we must work quickly to establish an international inventory of all weapons-grade fissile material. We must pledge full support to Russia's non-proliferation efforts by adequately funding the Cooperative Threat Reduction programs that ensure the safe dismantling of Russian warheads, safeguard Russia's nuclear materials and technology, and prevent the exodus of Russia's nuclear scientists. Since the non-proliferation regime will not last indefinitely as long as some countries are allowed nuclear weapons while others are denied them, the nuclear weapons states must make true on their promises to work for the eventual elimination of nuclear weapons. The United States should take a leadership role by pledging no first use of nuclear weapons, working with Russia to make deep cuts in our arsenals, and taking nuclear weapons off high-alert status.

The United States should re-enter negotiations toward a viable biological weapons regime, and strengthen the chemical weapons regime. We should support an International Court of Justice to deal broadly and multilaterally with terrorists and other war criminals.

Finally, we must promote sustainable development so that people have hope and the environment can sustain life. We must address the gross disparities of wealth on the planet and never demonize any peoples, for the dehumanization of others is the precondition for heartless killing.

We must be humble yet strong.