On August 6, 1945 the United States dropped a uranium-based atomic bomb over Hiroshima, Japan. The bomb, which had an explosive yield equivalent to about 15,000 tons of TNT, exploded at an altitude of about 1,900 feet and instantly killed more than 80,000 people. In 1952 Edward Teller conceived, and Richard Garwin drew, the plans for a hydrogen bomb. The device used a fission bomb to trigger an uncontrolled, self-sustaining reaction causing hydrogen isotopes to fuse. Their prototype had an explosive power of 10.4 megatons, the equivalent of just over 1,000 Hiroshima bombs exploding simultaneously. On November 1, 1952, a bomb weighing around 80 tons (160,000 pounds) code named Ivy Mike was test-fired on Elugelab Island in the Marshall Islands. After the explosion, most of the island had disappeared; all that was left was a crater with a diameter of 2 miles (3.2 kilometers) and 180 feet (54.9 meters) deep.

To make a long story short, in 1952 there were 841 nuclear bombs. By 1967 the count had peaked at 31,255. In simple terms, a single Ivy Mike dropped on a mega city could instantly kill 10 million people. Today, should there be a full nuclear exchange between the U.S. and Russia, and perhaps even China, Armageddon would result. Hypersonic intercontinental missiles outfitted with multiple independently-targetable reentry vehicles (MIRVS), nuclear powered submarines equipped with similar missiles, and strategic bombers, the so-called strategic triad, can obliterate life as we know it.

A 1-megaton device, one-tenth Ivy Mike’s yield, would generate a fireball 180 million degrees Fahrenheit (about 100 million degrees Celsius). Within seconds, its diameter would encompass about 1 mile (1.6 kilometers) causing metals to melt or evaporate, concrete to explode, and transform living organisms, including humans, into carbon. One bomb. To put things into perspective, both the U.S. and Russia have thousands of such bombs ready to be delivered at a moment’s notice; and China is fast catching up.

And it doesn’t stop there. Today there are plans to deploy missiles permanently in orbit a few hundred miles above their intended targets, only a few minutes flight time away. Considering that the proliferation of such technology will almost certainly eventually spread to all nuclear-armed nations, a real Sword of Damocles is hanging over humanity.

There is no question that this can happen at any time and without warning. As for the probability, it’s extremely high, whether by accident, human error, miscalculation, or intentionally. In fact, already there have been at least 12 occasions when the world has come very close to nuclear war, among them:

• In 1961 a malfunctioning switch in the US Strategic Air Command communications system led to a false alarm and a near miss.

• In October 1962 the US and the Soviet Union became entangled in a confrontation involving Soviet nuclear missiles in Cuba.

• In 1968 a B-52 carrying nuclear weapons crashed near Thule Air Base, prompting concerns about accidental nuclear use.

• In 1973, during Arab-Israeli War, the US raised its DEFCON level.

• In September 1983, a Soviet early warning system detected what appeared to be a US first-strike nuclear attack, but it was a false alarm due to a technical malfunction.

There are those among us who, consumed by hatred or ideology, would gladly trade their lives if they could only detonate a modern bomb in a perceived enemy’s megacity. That it has not yet happened does not mean it won’t. Accordingly, nuclear weapons must necessarily be ranked the greatest potential acute threat; and the only way to make sure they will never be used is by abolishing them -no exceptions. To paraphrase President Kennedy, “before they abolish us.” For that, all other converging issues must be simultaneously and satisfactorily resolved.