In recent years, nuclear weapons have seemed a Strangelovian anachronism - Cold War relics from the days when Leonid Brezhnev and Ronald Reagan glowered at one another, brandishing their missiles while the rest of the world quaked.
Today, the world's collective arsenal still includes thousands of nuclear weapons on hair-trigger alert at a time when the risk of accidental or unauthorized nuclear launch may in fact be increasing.
Meanwhile, as North Korea and other "rogue states" proceed with their nuclear weapons programs, the Pentagon itself is interested in a new generation of nukes designed specifically to attack an enemy's conventional military forces, including weapons of mass destruction hidden deep underground.
All of this comes as the United States, expressed in Bush administration policies, shifts its doctrine from deterrence in conjunction with NATO and other allies to unilateral preemption - attacking enemies before they become more dangerous rather than hoping to hold them off with the threat of overwhelming attack.
Many observers say the Cold War nuclear doctrine of "mutually assured destruction" (MAD) is obsolete, and so are nuclear weapons. But Defense Secretary Donald Rumsfeld argues just the opposite.
"Nuclear attack options that vary in scale, scope, and purpose will complement other military capabilities.... [providing] the range of options needed to pose a credible deterrent to adversaries," Mr. Rumsfeld states in the Pentagon's most recent Nuclear Posture Review.
Included as possible targets here are weapons of mass destruction as well as conventional enemy forces, including those tied to terrorist activities.
Over the objections of Democratic lawmakers, the Senate last week moved in this direction. It approved a Bush administration request to research new nuclear weapons designed for such circumstances.
The measure would lift the ban on development of low-yield nuclear weapons (those with no more than 5 kilotons of explosive force, which is about one-third the size of the bombs dropped on Hiroshima and Nagasaki at the end of World War II), and it provides funding to research a much larger bunker-busting bomb called the "Robust Nuclear Earth Penetrator."
Some read this as making nuclear war - or at least war that includes nuclear weapons - more "thinkable."
"The administration seems to be moving toward a military posture in which nuclear weapons are considered just like other weapons - in which their purpose is not simply to serve as a deterrent, but as a usable instrument of military power, like a tank, a fighter aircraft, or a cruise missile," Senator Dianne Feinstein (D) of California told fellow senators last week.
Senator Feinstein also expressed concern that this could lead other countries - some overtly threatening to US interests - to more actively pursue such weapons.
But Rumsfeld bristles at what he sees as a politically tinged rhetorical leap from investigating the possibilities of a new generation of tactical nuclear weapons to their deployment and use on a wide scale.
"It's not to develop. It's not to deploy. It's not to use. It's to study," Rumsfeld said at a press briefing last week.
In any case, raising the question of possibly pursuing new nuclear weapons comes in the same context of 21st-century warfighting as defending against such weapons of mass destruction. The Bush administration last week issued its "National Policy on Ballistic Missile Defense," saying that the program to shoot down enemy missiles is now intended to counter possible terrorist attacks using chemical and biological as well as nuclear weapons.
While tensions may have eased between the United States and Russia, a new study claims that risks from nuclear weapons possessed by both countries may be worse than during the cold war.
Among the reasons cited in a new RAND study: The two countries still keep some 8,000 nuclear warheads on alert; economic difficulties and weakened military forces mean Russian nukes are less stable and less secure; US nuclear weapons have become more capable and more accurate, which could increase the incentive for Russia to launch quickly in times of extreme stress.
"The risk has increased [of] a perfect storm in terms of nuclear miscalculation or an accident," warns former Senator Sam Nunn (D) of Georgia, head of the nonprofit group The Nuclear Threat Initiative, which commissioned the RAND study.