The plunging airliners, commandeered by terrorists, ripped gaping holes in more than the towers of the World Trade Center. They ripped away the veneer of security that we believed surrounded us. We in America can never again feel secure in the same way.

We were vulnerable before the hurtling planes crashed into the World Trade Center, but we never stopped to think that this could happen to us. Now we understand our vulnerability, and our lives will never be the same.

What madmen seek to kill us? Are the plans for the next attacks already set in motion? Are there more suicidal phantoms, coiled like cobras, in our midst? We remain apprehensive with good reason.

Some Americans are calling for vengeance. But we are fighting phantoms, and our military power is not sufficient to assure an end to future threats. It will not be so easy to find these terrorists and bring them to justice.

The best of America is on display. Heroism abounds. Americans are coming together to mourn their losses, to grieve, to comfort and care for each other, and to begin rebuilding. All Americans have a piece of that gaping hole in their hearts.

Justice must be done, and we need to find those responsible for the crimes committed. But our response to those crimes must be legal under international law, moral in not causing the deaths and injuries of more innocent people, and thoughtful in asking why this has occurred and what can be done to end the cycle of violence.

Vengeance may reassure some that our power matters. But vengeance will not protect us. It will only create more who despair and hate, more who are ready to rip at the heart of America.

Until all are secure, none will be. The violence could grow even worse because the weapons in our world can kill so massively. Nuclear, radiological, chemical and biological weapons all hover around us. Will we take the necessary steps to end these threats?

There are deeper issues that we must explore. These include questions about who we are and what we are doing in the world and to the world. In the end, our only way out is to climb through the hole in our hearts until we find our full humanity.

The only way we can mend our hearts is to recognize our oneness with all humanity. For better or worse, we share a common shadow and a common fate. We cannot change the past, but we can begin building a more peaceful and decent world today.

*David Krieger is the President of the Nuclear Age Peace Foundation.