This article was originally published on the History News Network

This August, when hundreds of Hiroshima Day vigils and related antinuclear activities occur around the United States, many Americans will wonder at their relevance. After all, the nuclear danger that characterized the Cold War is now far behind us, isn’t it?

Unfortunately, it is not.

Today there are nine nuclear-armed nations, with over 23,000 nuclear weapons in their arsenals. Thousands of these weapons are on hairtrigger alert.

Admittedly, some nations are decreasing the size of their nuclear arsenals. The United States and Russia–which together possess about 95 percent of the world’s nuclear weapons–plan to sign a treaty this year that will cut their number of strategic weapons significantly.

But other nations are engaged in a substantial nuclear buildup. India, for example, launched the first of its nuclear submarines this July and is also developing an assortment of land-based nuclear missiles. Meanwhile, Pakistan has been busy testing ballistic missiles and cruise missiles that will carry nuclear warheads, as well as constructing two new reactors to make plutonium for its expanding nuclear arsenal. Israel, too, is producing material for new nuclear weapons, while North Korea is threatening to resume its production.

In addition, numerous nations–among them, Iran–are suspected of working to develop a nuclear weapons capability.

But surely national governments are too civilized to actually use nuclear weapons, aren’t they?

In fact, one government (that of the United States) has already used atomic bombs to annihilate the populations of two cities.

Moreover, nations have come dangerously close to full-scale nuclear war on a number of occasions. The Cuban missile crisis is the best-known example. But there are numerous others. In October 1973, during a war between Israel and Egypt that appeared to be spiraling out of control, the Soviet government sent a tough message to Washington suggesting joint–or, if necessary, Soviet–military action to bring the conflict to a halt. With President Richard Nixon reeling from the Watergate scandal and drunk in the White House, his top national security advisors responded to what they considered a menacing Soviet move by ordering an alert of U.S. nuclear forces. Fortunately, cooler heads prevailed in the Kremlin, and the sudden confrontation eased short of nuclear war.

Of course, nuclear war hasn’t occurred since 1945. But this fact has largely reflected public revulsion at the prospect and popular mobilization against it. Today, however, lulled by the end of the Cold War and the disintegration of the Soviet Union, we are in a period of relative public complacency. In this respect, at least, the situation has grown more dangerous. Without countervailing pressure, governments find it difficult to resist the temptation to deploy their most powerful weapons when they go to war. And they go to war frequently.

Furthermore, while nuclear weapons exist, there is a serious danger of accidental nuclear war. In September 1983, the Soviet Union’s launch-detection satellites reported that the U.S. government had fired its Minuteman intercontinental ballistic missiles, and that a nuclear attack on the Soviet Union was underway. Luckily, the officer in charge of the satellites concluded that they had malfunctioned and, on his own authority, prevented a Soviet nuclear alert. The incident was so fraught with anxiety that he suffered a nervous breakdown.

Another nuclear war nearly erupted two months later, when the United States and its NATO allies conducted Able Archer 83, a nuclear training exercise that simulated a full-scale nuclear conflict, with NATO nuclear attacks upon Soviet nuclear targets. In the tense atmosphere of the time, recalled Oleg Gordievsky, a top KGB official, his agency mistakenly “concluded that American forces had been placed on alert–and might even have begun the countdown to nuclear war.” Terrified that the U.S. government was using this training exercise as a cover behind which it was launching a nuclear attack upon the Soviet Union, the Soviet government alerted its own nuclear forces, readying them for action. “The world did not quite reach the edge of the nuclear abyss,” Gordievsky concluded. But it came “frighteningly close.”

Furthermore, today we can add the danger of nuclear terrorism. Although it is very unlikely that terrorists will be able to develop nuclear weapons on their own, the existence of tens of thousands of nuclear weapons and of the materials to build them in national arsenals opens the possibility that terrorists will acquire these items through theft or black market operations.

Overall, then, the situation remains very dangerous. Dr. Martin Hellman, a Professor Emeritus of Engineering at Stanford University who has devoted many years to calculating the prospects of nuclear catastrophe, estimates that the risk of a child born today suffering an early death through nuclear war is at least 10 percent. Moreover, he cautions that this is a conservative estimate, for he has not included the danger of nuclear terrorism in his calculations.

In June 2005, Senator Richard Lugar, then the Republican chair of the Senate Foreign Relations Committee, produced a committee report that was even less sanguine. Asked about the prospect of a nuclear attack within the next ten years, the 76 nuclear security experts he polled came up with an average probability of 29 percent. Four respondents estimated the risk at 100 percent, while only one estimated it at zero.

Thus, Hiroshima Day events provide a useful context for considering the ongoing nuclear danger and, conversely, the necessity for a nuclear weapons-free world.

Lawrence Wittner is Professor of History at the State University of New York/Albany. His latest book is Confronting the Bomb: A Short History of the World Nuclear Disarmament Movement (Stanford University Press).