A new report by my organization, “Nuclear Weapons: The State of Play,” shows that pockets of progress on nuclear security, nonproliferation and disarmament are overshadowed by the drag of historical inertia on nuclear weapons programs, arsenals, doctrines and deployments.

In their fifth joint article in the Wall Street Journal (March 6), Henry Kissinger, Sam Nunn, William Perry and George Shultz focus on four issues: nuclear security, followup actions after the new Russia-U.S. START accord, a new verification and transparency initiative, and taking nuclear warheads off high alert levels.

The security environment of the 21st century is starkly different, but U.S. and Russian nuclear force postures are still trapped in the old Cold War paradigm. Immobilized by historical inertia, they maintain nearly 2,000 nuclear warheads ready to launch within minutes.

A new study published by a U.N. institute concludes that current nuclear alert levels “are deeply rooted in Cold War thinking, vastly exceed current and foreseeable security needs, and undercut efforts to reduce” the role of nuclear weapons.

Amen. The haste in which the decision to use nuclear weapons on high alert must be made in response to a suspected incoming attack carries enormous risks. Maintaining nuclear arsenals on high alert undermines efforts to hold the line on proliferation, is hugely expensive and increases the risk of accidental, unauthorized, misinformed or premature use of nuclear weapons.

In a March 29, 2012, conversation, the national security adviser during the Carter administration, Zbiegniew Brzezinski, recalled being woken up by a call at 3 a.m. from his military assistant. The general told him the United States was “under nuclear attack” and that 200 Soviet missiles fired “30 seconds ago” would hit in 30 minutes. He had three minutes to notify the president, who would have four minutes to decide how to respond. With two minutes left, the alarm was shown to be false and Brzezinski did not have to wake the president.

What if the false alarm confirmation had come after (a) the initial three minutes, (b) seven minutes and the president had ordered the launch of U.S. missiles, or (c) 30 minutes as the U.S. missiles were about to hit Soviet targets? In the middle of a crisis, if decisions on using nuclear weapons must be made very quickly, the possibility grows of miscalculation or a decision based on the wrong information.

Taking nuclear warheads and systems off high alert can deepen the stability of nuclear deterrence so that nuclear armed rivals will not attack each other regardless of any rise in tension between them.

Opponents argue that de-alerting could undermine strategic stability. High alert levels have not been a bar to improved Russia-U.S. relations. Crisis stability is reduced when a potential enemy, who has cheated by either failing to de-alert fully or by secretly re-alerting, has an incentive to launch an attack during a tense standoff before “re-alerting” has been completed by the nuclear adversary.

This is a questionable claim. There is no plausible scenario under which either Russian or U.S. second-strike retaliatory capability could be decapitated even if they had all nuclear weapons off alert. Nuclear weapons not on alert would remain survivable so that they don’t lose their deterrent function and there is no incentive to engage in a re-alerting race.

De-alerting is a strategic step in downgrading the military role of nuclear weapons and transforming relations between nuclear adversaries from one of strategic confrontation to strategic collaboration. It is a confidence-building measure both directly among nuclear powers, and between them and the rest.

Indefinite reliance on nuclear weapons through doctrines and deployment postures of high operational readiness can legitimize the nuclear ambitions of others who cannot otherwise be convinced that nuclear weapons are playing a reduced role in post-Cold War national security strategies.

The reality is that whether the alarm about an incoming nuclear attack turns out to be genuine or false matters little. In the real world, the sole purpose of nuclear weapons can only be deterrence — neither defense nor retaliation. There is no conceivable circumstance in which Russia or the U.S. could launch massive nuclear strikes against the other without committing nuclear suicide itself. For there is no conceivable circumstance in which either party can be certain of destroying the other’s nuclear retaliatory capability.

Even if all fixed site weapons and missiles could be destroyed in a surprise attack — regardless of how many nuclear weapons the enemy has on high alert — Russia would have more than enough road-mobile intercontinental missiles and the U.S. more than enough sea and air-based weapons to destroy each other.

If enemy weapons have already been launched, hitting back with nuclear strikes while they are in flight or after they have hit makes no difference to the casualties and damage to one’s own side. At worst, it will stop “us” from destroying “them” several times over instead of only once. Waiting until after enemy strikes are confirmed may leave them with the arsenal to destroy us more than once. But it is certain that both sides will suffer catastrophes even if one side waits until after it is actually hit.

Conversely both will be substantially better off with a deferred decision if the suspicion proves to have been a false alarm. The logic of keeping nuclear forces and systems on high alert, to be launched on a short decision-making fuse, collides with the strategic logic of nuclear survivability.

Alert status is unnecessary and irrelevant against nonnuclear rivals. Nuclear war cannot be fought and won against nuclear rivals at acceptable cost. High alert levels are not necessary for stable deterrence.

Like nuclear terrorism, the contingency of a launch of nuclear weapons on high alert by mistake, miscalculation or malfunction is low probability but high impact. Lowering the operational status of nuclear weapons and lengthening the decision-making process to use them would reduce the risk of accidental or unintended nuclear war and also provide a much-needed practical boost for disarmament and nonproliferation.

Ramesh Thakur is director of the Centre for Nuclear Non-Proliferation and Disarmament at the Crawford School of Public Policy, Australian National University (ramesh.thakur@anu.edu.au).