The world may be teetering on the edge of a worrisome new phase in the sixty-year-old age of atomic weapons.
North Korea now has the bomb, probably. Iran may seek nuclear devices of its own. India's stockpile of weapons-grade fissile material could soon grow larger - thanks to a controversial new treaty with the US.
Meanwhile, efforts to strengthen the Nuclear Non-Proliferation Treaty have stagnated. Last year's NPT review conference fell apart amid international bickering.
Will nukes now become must-haves for more nations? Asked for their worst-case scenario, experts say there could be 10 new members of the nuclear club by 2015.
"There's an urgent need to take more drastic measures" to prevent the spread of atomic weapons and technology, said Nobuaki Tanaka, UN Under-Secretary- General for Disarmament Affairs, at a conference in Washington last week.
First, the good news: Viewed through the long lens of history, the globe's struggle to control the genie of nuclear weapons might be judged remarkably successful, so far.
The number of nations with a nuclear arsenal, officially at seven, is far smaller than US intelligence reports of the 1960s predicted it would be. Most important, no atomic weapon has been detonated in anger since the US dropped the Hiroshima and Nagasaki bombs in 1945.
This non-use wasn't foreordained. Back in the early 1960s, when ads for bomb shelters were a common sight, many experts thought it was only a matter of time until someone dropped a bomb.
Back then, Harvard University asked strategic theorist Thomas Schelling to serve on a committee to identify university buildings that might serve as fallout shelters - and who might be admitted to them in a time of crisis.
"If I had said, 'Oh, come on, nobody is going to use nuclear weapons for the next 40 years,' everybody would have thought I was out of my mind," said Mr. Schelling at a March Council on Foreign Relations meeting in New York.
Schelling, now a professor at the University of Maryland, considers nuclear non-use such a remarkable development that he made it the theme of his acceptance address before the Swedish Academy when he won the Nobel Prize in economics in 2005.
Now, the bad news: Events in recent years may have begun to undermine the taboo against nuclear use. At the least, the world faces the prospect of a new wave of nuclear proliferation. And that could roil some of the globe's most unstable regions.
"Over the last decade, there has been a serious and dangerous loss of momentum and direction in disarmament and non-proliferation efforts," concluded a Swedish-financed international commission in a lengthy report released last week.
This effort, headed by former UN weapons inspector Hans Blix, laid part of the blame for this decay on US unilateralism, shown through such actions as Washington's refusal to ratify the Comprehensive Nuclear Test Ban Treaty.
But other experts point to a wide array of causes. According to UN Under-Secretary-General Tanaka, India's surprise nuclear tests in 1998 accelerated the South Asian arms race. Then came North Korea, and the hermit kingdom's determined - and clandestine - efforts to produce atomic arms.
Iran's nuclear activities may have further undermined confidence in the nuclear Non-Proliferation Treaty and the general world non-proliferation regime. The extent of Pakistani nuclear scientist Abdul Qadeer Khan's illicit trafficking in weapon plans shocked much of the world.
Then there is the apparent disinclination of big nuclear powers to give up their weapons, or at least make significant moves toward disarmament, Tanaka says.
"Why should others not wish to emulate them?" he said at last week's conference, held by the UN Association of the US.
In this context, the US offer to sit down and talk directly with Iran - if it suspends nuclear enrichment activities - is a positive development, say arms control advocates. So far, Iranian officials have rejected the notion of preconditions, but not that of the talks themselves.
At the Conference on Disarmament, in Geneva, US officials have also offered a draft of a treaty that would ban all future production of fissile material for bombs.
And administration officials reject the notion that the US nuclear weapons stockpile sets a bad example for others. They say they've lived up to the terms of the Nuclear Non-Proliferation Treaty, which requires the big-weapons states to move toward nuclear disarmament.
By 2012, the US arsenal of deployed nukes will be 80 percent smaller than it was 1990, according to Andrew Semmel, deputy assistant secretary of state for nuclear non-proliferation.
"The US nuclear stockpile continues to dwindle," said Semmel at the UN Association event.
But critics point out that many of those weapons are simply being withdrawn from service, not disassembled and destroyed.
To help address the current proliferation crisis, the US should reconsider its rejection of the Comprehensive Test Ban Treaty, say arms control advocates. It should continue efforts to stop the spread of fissile material and recognize that legitimate security concerns drive some nations toward reliance on nukes.
Some are urging Congress to reject the new US nuclear deal with India. Under this pact, signed March 2 by President Bush and Indian Prime Minister Manmohan Singh, India would receive US expertise and fuel for civilian nuclear power plants. In return, India would separate its military and civilian nuclear infrastructures, and agree to some international inspections.
The inspections would be a first for India, which is not a signatory of the NPT. But critics claim the deal would simply free up more of India's domestic fissile material production for weapons use, allowing it to built its arsenal faster.
"The benefits are vastly overstated and its damage to the world proliferation regime high," says Daryl Kimball, executive director of the Arms Control Association.
Of course, there is also this difficult question: What do we do if we fail? It's possible that nothing the world can do will dissuade North Korea or Iran from decisions to pursue nuclear weapons.
There's the option of military action, of course. But that would be extremely risky, and even if successful might only delay proliferation, not stop it.
Schelling believes it is important to try and reach officials or experts in these nations and discuss nuclear stewardship. Over decades, the Soviet Union and the US developed a mutual view on the nature of nuclear deterrence that made the cold war standoff stable, though still frightening.
Defense intellectuals from India and Pakistan have been coming to meetings in the West for years, and have a very good idea of what nuclear weapons are and are not good for, said Schelling at the Council on Foreign Relations meeting.
But representatives of Iran and North Korea haven't. They haven't heard lengthy discussions about the importance of nuclear chains of command, for example.
"I think if you get people thinking about these issues, then they're going to begin to think more carefully about, 'What are these weapons good for?'" said Schelling.