It’s now part of our common vernacular to say “everything changed” after September 11th. When a domestic airliner can be turned into a missile guided by anger and hatred, we are all vulnerable.

But as we confront this new war on terrorism we must remember what did not change on September 11th: The greatest potential danger to the U.S. and world remains the threat posed by nuclear weapons. The nightmare scenario of fundamentalists in a destabilized Pakistan getting control of nuclear weapons is but one example of potential dangers.

We are reminded of this because 10 years ago this month the world was also in a time of great tension and instability. The Soviet Union was breaking up and President George Bush Sr. took steps to reduce the threat of nuclear war by taking a significant number of U.S. nuclear weapons–in Europe and the U.S.–off high-alert status.

In response to the President’s initiative, President Gorbachev reciprocated by de-alerting comparable numbers of Russian nuclear weapons.

While these actions helped the nuclear superpowers back away from using weapons of mass destruction at a precarious time, it’s sobering to note that the U.S. and Russia are still courting nuclear disaster. Despite no longer being strategic foes, they still maintain thousands of nuclear weapons on hair-trigger alert–poised for a quick launch. This is a threat that no missile defense system will ever be able to protect us from.

Keeping nuclear weapons on a hair-trigger means that leaders on both sides have just minutes to assess whether a warning of an attack is real or false. And while the threats we faced during the cold war came from Soviet strength–the danger today comes more from Russia’s weakness.

For example, Russia’s troubled economy has led to the profound decay of their early warning satellite system. A fire last May that destroyed a critical facility used to control Russian warning satellites has made things even worse. Dr. Bruce Blair, President of the Center for Defense Information, has concluded, “Russia has completely lost its space-based early warning capabilities. In essence, their ability to tell a false alarm from a real warning has been nearly crippled.”

False alarms on both sides have already brought us to the brink of nuclear war. What will happen now if there is a war in the volatile neighborhood of Central Asia–a region that includes nuclear powers India, Pakistan … and Russia?

Former Senator Sam Nunn brought the point home in a recent speech: “The events of September 11 gave President Bush very little time to make a very difficult decision–whether to give orders to shoot down a commercial jetliner filled with passengers. Our current nuclear posture in the U.S. and Russia could provide even less time for each president to decide on a nuclear launch that could destroy our nations.”

Mr. Nunn called on Presidents Bush and Putin to “stand-down” their nuclear forces to “reduce toward zero the risk of accidental launch or miscalculation and provide increased launch decision time for each President.”

In the spirit of the courageous steps his father took to decrease the nuclear threat 10 years ago, President Bush can and should take action now to remove nuclear weapons from hair-trigger alert. This would send a signal to the world that in this volatile time, the U.S. is serious about preventing the use of nuclear weapons.