For nearly 40 years, American presidents have expressed their intention to fulfill the US obligation under the 1968 nuclear Nonproliferation Treaty (NPT) to pursue "effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament."

Still, few presidents have taken that goal seriously, and those who did missed historic opportunities to move closer toward a nuclear weapons-free world. Beginning with the next US president, that can and must change, or else the global effort to reduce the risk of nuclear war, curb proliferation, and prevent catastrophic terrorism will falter.

As George Shultz, William Perry, Henry Kissinger, Sam Nunn, and more than two dozen other former Republican and Democratic government officials have written in essays in The Wall Street Journal, we are approaching "a nuclear tipping point."

If Washington is not serious about disarmament, states in the non-nuclear-weapon majority will continue to resist new measures to restrict the spread of bomb-making technologies, improve verification, and enforce NPT compliance. This is a chief reason why Shultz et al. have called on the United States to reaffirm the goal of a world free of nuclear weapons and pursue immediate steps toward that end.

Each of the three remaining presidential candidates have expressed rhetorical support for renewed US action on disarmament. To reestablish US legitimacy on nonproliferation, the next president must translate words into dramatic and meaningful action in three key areas.

First, the next president must pursue dramatic and irreversible reductions in US and Russian nuclear arsenals, which together total more than 10,000 warheads. The White House and the Kremlin have not been able to agree on follow-on measures to the 1991 Strategic Arms Reduction Treaty (START) and verification provisions, which are due to expire in December 2009. This is due in large part to President George W. Bush's resistance to Russian proposals to reduce deployed strategic nuclear forces below 1,700-2,200 warheads. To "hedge" against unforeseen and unspecified dangers, Bush also opposes treaty-mandated missile reductions and seeks to build new warheads and bolster the US weapons production complex.

Yet, with the end of the Cold War, there is no plausible reason for the US and Russian leaders to maintain thousands of strategic nuclear weapons on high alert. Besides the United States and Russia, no state possesses more than 400 nuclear warheads. Massive arsenals capable of annihilating entire nations within an hour are more of a liability than an asset because they breed mistrust and worst-case assumptions among other states and perpetuate the risk of accidental or unauthorized launch.

New thinking can and should lead to a new treaty that results in dramatically deeper reductions of all types of US and Russian nuclear warheads­to 1,000 or less­ and lower ceilings on the strategic missiles. With streamlined START-style verification, the agreement could restore confidence that each country will actually dismantle, not simply warehouse, warheads and missiles. To avoid missteps, each state also can move to increase the time necessary to launch nuclear strikes.

Second, as Shultz and others suggest, the next president must lead a new, bipartisan effort to reconsider and ratify the Comprehensive Test Ban Treaty (CTBT) at an early date, which is considered to be a litmus test of the commitment of nuclear-weapon states to disarmament. Convincing the Senate of the nonproliferation value and verifiability of the treaty, as well as the ability of the United States to maintain its existing stockpile under a permanent CTBT, is difficult but possible.

Unfortunately, some have offered unnecessary compromise measures that would undermine the purpose of the test ban. Former Secretary of Defense Harold Brown, former CIA Director John Deutch, and others have suggested adopting Bush's costly plan for new, so-called "reliable" replacement warheads to buy support from CTBT skeptics.

Such proposals are politically risky and shortsighted. Not only is the US capability to maintain its existing stockpile more than adequate, but the production of a new generation of warheads could lead to calls to test the new designs and would undermine the chief value of the CTBT to disarmament and the NPT: ending new warhead development. If pursued, other states would see the United States as circumventing the CTBT and conclude it is of little benefit.

Third, the next president must also reassess and radically reduce the role of nuclear weapons. Today, there is no conceivable circumstance that justifies the use of US nuclear weapons to fight a non-nuclear adversary. Policies that assert a war-fighting role for nuclear weapons only deepen the risk of proliferation. The next president should declare that the United States will not use nuclear weapons first or against states that do not possess such arms.

Not surprisingly, the cynics and supporters of the nuclear status quo believe action toward a nuclear weapons-free world is an exercise in wishful thinking. The real fantasy, however, is to expect nuclear restraint and greater commitment to nonproliferation from other states in the absence of bold US action on disarmament.

Daryl Kimball became the Executive Director of the Arms Control Association in September 2001. The Arms Control Association (ACA) is a private, non-profit membership organization dedicated to public education and support of effective arms control measures pertaining to nuclear, chemical, biological, and conventional weapons.

This article was previously published under the title "Getting Real About Nuclear Disarmament" here.