We live in a dangerous world. Hostile nations are rushing to produce nuclear weapons of awesome power. Terrorist groups plot each and every day to find new ways to kill Americans. Violence in the Middle East is reaching a deadly new scale.

Like it or not, America has a responsibility to do what it can to make this a safer world — not as global policemen, but for ourselves, for our children, for our security, and for the freedom and democra-

cy that we hold dear. That’s what should motivate our defense policy and our foreign policy.

In considering the fiscal 2004 Defense authorization bill, the Senate took a dangerous step forward in the development of new nuclear weapons. We loosened the ban on research into low-yield nuclear weapons.

These weapons are called “mini-nukes,” but they are far from the type of benign, surgical-strike weapons that the name suggests. Mini-nukes are a dream come true for rogue regimes and terrorists. One of these weapons, carried by a terrorist in a suitcase, can destroy an entire town. A 5-kiloton nuclear weapon is half the size of the Hiroshima blast.

Some claim that these weapons will be used against deeply buried, hardened bunkers. However, they are seeking the technologically impossible. Current technology will allow a warhead to burrow up to 50 feet into the ground. Detonating even a 1-kiloton nuclear weapon at that depth will create a crater larger than the World Trade Center, larger than a football field. It will spew a million cubic feet of radioactive dust into the atmosphere.

We must say to the rest of the world that, though we may conduct research into these weapons, we will never develop them. In doing so, we can encourage the rest of the world to follow our example and not develop these weapons. To do otherwise would be to embrace a “Do as I say, not as I do” defense policy. We must lead the way in reducing our reliance on nuclear arsenals. [IMGCAP(1)]

There’s a reason that arms control has been such a key element of our foreign and defense policy over many decades. And the result has been that since Hiroshima and Nagasaki, no nuclear weapons have been used in war.

What’s at risk is not just intellectual research into low-yield nuclear weapons. The policy the Bush administration proposes jeopardizes the entire architecture of nuclear arms control that was carefully negotiated by our leaders over our lifetimes, starting with the Eisenhower administration.

Many cannot recall that fateful day in August 1945, when a high-flying B-29 bomber dropped the first nuclear weapon, “Little Boy,” over Hiroshima. More than 4 square miles of the city were instantly and completely destroyed. More than 90,000 people died instantly. Another 50,000 died by the end of that year. Three days later, another B-29 dropped “Fat Man” over Nagasaki, killing 39,000 people and injuring 25,000 more.

In 1957, the Soviets launched Sputnik, and it became clear that two oceans could not protect us from a nuclear attack at home.

In July 1968, the treaty on the nonproliferation of nuclear weapons was signed in Moscow, London, and Washington, D.C., and entered into full force in March 1970. For the next 20 years, the United States and the Soviet Union negotiated a remarkable series of treaties to reduce both the size and our reliance on nuclear arsenals.

To those who would say that our efforts at arms control have not prevented the spread of nuclear weapons, I would point out that in the past 15 years, South Africa, Belarus, Kazakhstan and the Ukraine — the world’s third-largest nuclear power — renounced the use of nuclear weapons and joined the NPT as non-nuclear states. Two nuclear states, Britain and France, ratified the Comprehensive Test Ban Treaty. The United States and Russia have removed thousands of nuclear weapons from alert status, reduced the number of weapons, and collaborated in securing fissile material from theft.

If we lift this ban, we turn our backs on almost five decades of progress in reducing the threat of nuclear weapons against America and Americans.

Some in the administration argue that, in today’s world situation, the yield of the nuclear weapons in our current arsenal is so immense that our enemies know that we are reluctant to use them. They argue, therefore, that these massive nuclear weapons have limited deterrent value against our adversaries, and that we must develop smaller, more “usable” nuclear weapons to make deterrence more credible.

In fact, if we start treating nuclear weapons as just another explosive in our arsenal, rather than as a weapon of last resort, we will increase the likelihood of their use, not only against our adversaries, but also against ourselves. This change would dangerously blur the line between nuclear and conventional weapons, and tear down the firewall between these weapons that has served us so well in preventing nuclear war in the entire half-century since World War II.

As Secretary of State Colin Powell said in 2002, “Nuclear weapons in this day and age may serve some deterrent effect, and so be it, but to think of using them as just another weapon in what might start out as a conventional conflict in this day and age seems to me to be something that no side should be contemplating.”

It is difficult to believe as well that these new types of nuclear weapons serve any rational military purpose. As we witnessed in the first Persian Gulf War, and again in the recent war against Iraq, precision-guided conventional munitions and standoff weapons serve us very well. Low-yield weapons would be no more effective than precision-guided conventional weapons, and their radioactive fallout would be far more dangerous to our ground troops and to civilian populations. Our goal is to prevent nuclear wars, not start them.

Sen. Edward Kennedy (D-Mass.) is a member of the Armed Services Committee.