Despite the pressures of campaign season, it will be important for John McCain and Barack Obama to stay united on one theme -- reducing and eventually eliminating the world's stockpile of nuclear weapons. Both have said they support that goal.

This is especially critical at a time of increased tension with Russia, upheaval in Pakistan and concerns about the nuclear aspirations of North Korea and Iran. While the Cold War is over, the world is perhaps a more dangerous place than ever, thanks to the profusion of states and nonstate actors who would like to acquire nuclear capabilities.

The United States and Russia have about 95 percent of the world's nuclear weapons and have committed to whittling down those stockpiles. But the United Kingdom, France, China, Israel, India, Pakistan and North Korea also have nuclear weapons, which makes it a more difficult matter to achieve global consensus. Yet it's important to apply concerted diplomatic pressure toward this goal.

More than two-thirds of the respondents to a poll released last week by the Campaign for a Nuclear Weapons-Free World said they believe that the possession of nuclear weapons by some countries encourages other countries to acquire their own. This seems a reasonable conclusion, based on a nation's natural instinct to protect itself against perceived threats. Nations must act in their own self-interests in matters of military strength, trade and regulatory policy.

But the nuclear threat is of an entirely different order. Consider that the atomic bombs that fell on Japan are believed to have killed about 340,000 within five years of their detonation. And consider that subsequent bombs developed by the United States and the Soviet Union were believed to be more than 1,000 times as powerful as the ones used in World War II. And while the United States and the USSR built enormous arsenals and pointed them at each other, each recognized that a nuclear war would devastate both nations. Their mutual fear kept the Cold War from turning hot.

Ronald Reagan and Mikhail Gorbachev came together to strike a deal to reduce the number of nuclear weapons, which signaled a turning point in the way the world had come to regard them. They were no longer, as Gorbachev said, a tool for national security.

Yet the Strategic Arms Reduction Treaty is due to expire late next year. And the reductions agreed to in the Moscow Treaty on Strategic Offensive Reductions haven't been completed. Meanwhile, some startling episodes, such as last year's temporary misplacement of six nuclear missiles by the U.S. Air Force, show that the nuclear threat remains latent and lethal.

Obama and McCain have each spoken forcefully about the need to stop the spread of nuclear weapons and to reduce the inventory that exists. They should continue to insist that the job of the next president should include doing exactly that.

Link to full article in the Oregonian