A nuclear-free world? Not yet.

When Ronald Regan was president, he scheduled a weekly one-on-one meeting in the White House with Secretary of State George Shultz. Nobody else was present, so when Secretary Shultz returned to the State Department, four or five of us senior advisers were always eager for a debriefing on what had been discussed and decided.

On one of these occasions, Shultz returned to announce that Reagan had become committed to ridding the world of nuclear weapons. A startled Richard Burt, then assistant secretary for European affairs, blurted out: "He can't do that!" following up with the conviction that replacing the US nuclear deterrent with conventional weaponry and troops would be of astronomical cost.

Shultz stared at us with those pale, impassive blue eyes that had served him so well as a negotiator in private life and government. You guys "had better get on the ball," he said. The president meant it, he said, and we were to work toward it.

Reagan, like presidents before him who had dreamed of a nuclear-free world, never achieved his goal, although he came close to persuading the Soviets at a 1986 summit in Reykjavik, Iceland.

On his first trip to Europe as president, Barack Obama affirmed the US commitment to a world free of nuclear weapons. Shultz, along with other formidable foreign-policy luminaries such as former Secretary of State Henry Kissinger, former Secretary of Defense William Perry, and former Senator Sam Nunn, have previously expressed the same hope.

Wisely, President Obama warned that such a goal "will not be reached quickly – perhaps not in my lifetime."

That may be an understatement.

A recent Council on Foreign Relations blue ribbon task force on US weapons policy finds that "the geopolitical conditions that would permit the global elimination of nuclear weapons do not currently exist." And a recent Department of Defense task force, chaired by former Secretary James Schlesinger, found that nuclear weapons remain "fundamental to deterrence." As one participant in the task force's review of US nuclear readiness put it: "Global disarmament of nuclear weapons is fine as long as we are sure we have the last one to be destroyed."

Global nuclear disarmament remains an eminently worthy goal. But it cannot be achieved in today's climate, while:

•A nation with fickle leadership such as North Korea develops nuclear weapons.

•Terrorist groups yearn to acquire one.

•Syria may aspire to join the nuclear club.

•Iran, despite its protestations of peaceful nuclear development, is probably developing nuclear weaponry.

•Pakistan and India will not surrender their nuclear weapons so long as they distrust each other.

•Israel (although it does not discuss its nuclear weapons) will not forgo them so long as challenged by unfriendly neighbors or groups.

What can happen is a reduction of existing nuclear arsenals. The US and Russia possess 90 percent of the world's nuclear weapons – far more than they want, or are needed for deterrence. Obama and Russian President Dmitry Medvedev are scheduled to meet in Moscow next month. It is expected that a draft treaty to replace the expiring 1991 Strategic Arms Reduction Treaty (START) will be on their agenda. It would further decrease the number of nuclear warheads each of them agreed to in START.

Next year, signatories to the Nuclear Non-Proliferation Treaty (NPT) are scheduled to review, and hopefully revise, that document. Launched in 1968, it legalizes the right of the US, Britain, Russia, China, and France to have nuclear weapons but called upon them to reduce, and ultimately disband, their nuclear arsenals. In exchange, some 180 nations not bearing nuclear weapons agreed not to develop them.

Over the years, the treaty has become tattered as countries such as North Korea have opted out of it, countries such as Iran are in it but not observing it, and countries such as Pakistan and India have developed nuclear weapons outside it.

At a press conference in April, Obama said the US and Russia would be in a stronger position to re-invigorate the NPT if they were leading by example.

Reductions in nuclear arsenals would be a plus. A nuclear-free world is but a mirage.

John Hughes, a former editor of the Monitor, served as assistant secretary of State in the Reagan administration. He writes a biweekly column.