There is an unsettling paradox in much of the recent debate over nuclear weapons in this country. Some pundits, fixated on purging “Cold War thinking” from those of us with real-world responsibilities for nuclear deterrence, are themselves suffering from thoughts frozen in time. In the midst of this important debate, let me offer some examples of the new strategic concepts emerging from a new generation of deterrence thinkers.

The conventional wisdom is that a world with fewer nuclear weapons is inherently a better world. What we are discovering is that less is not less, less is different.

US policy has led in reducing nuclear weapons. At its peak in 1967, the US stockpile stood at a staggering 31,255 warheads. Just since 1991, we have disassembled more than 13,000 weapons, and in the past decade taken our stockpile – the total number of weapons — down from 10,526 in 2001 to 5,113 in 2010. Our nuclear weapons and delivery platforms now number an order of magnitude less than during the Cold War, and this policy continues — creating new conditions in the global nuclear balance.

In this new nuclear environment, potential adversaries are reaching conclusions we did not expect, and our allies and partners are more nervous about it than we want them to be. This new world of several contending nuclear powers behaves differently than the bi-polar world that preceded it.

Deterrence is no longer (if it ever really was) a rational actor systems model; it works as a mental model. It’s more like the “hot hand” rule in basketball – players do not keep mental statistics on who has the highest percentage shot for a particular game situation; instead they carry a moving mental image of who at that moment is on a streak and feed the ball to that player instinctively. The same kind of thing happens in crisis and conflict. Behavioral scientists call this “fast, frugal heuristics,” and are beginning to explore the empirical dimensions of this 21st century deterrence dynamic.

There are some surprising findings and insights.

First, just because no one has detonated a nuclear weapon in war since 1945, does not mean they are sitting idly by, with little purpose. Nuclear weapons are in fact “used” every day — not to win a war, but to deter any adversary from thinking they could get away with starting one. As budget pressures rise, many call for not spending more on weapons we cannot use in the kinds of conflicts most likely to occur – presumably counter-terrorism or conventional warfare. But a nuclear war is the conflict we need to make sure remains the least likely to happen.

Second, there is much new research on 21st century deterrence of rogue actors and terrorists. We now know that, during the 1991 Persian Gulf War, Saddam Hussein was persuaded that if he were to order use of chemical weapons against US troops, the US would have responded with tactical nuclear weapons.

Hussein had extensive discussions with his generals – lectures really – and injected that assumption into all their war planning. Such thinking likely resides within the decision-making processes of other states that face a similar calculus. There is merit in reinforcing such fears among others who would harm their neighbors. It turns out that terrorists, even suicide bombers, harbor visceral fears of nuclear weapons, fears that can be exploited to deter them from acting should they ever get one.

Islamic terrorists adhere to the Koran’s proscriptions against poisoning the earth with radiological effects and creating mass casualties among the innocent. Cyber and psychological campaigns can broadcast messages across terrorists’ own social networks to convey this narrative challenge to terrorists’ intent. Terrorist cells also fear failure, so technical sabotage, misinformation and deception can magnify doubt about the prospects for a successful detonation.

Third, US nuclear weapons serve as a powerful instrument of nonproliferation. Post-Cold War experience reveals that others, from Saddam’s Iraq, to North Korea, Libya, Iran and others, pursue nuclear weapons as the centerpiece of an asymmetric counter to the United States’ conventional military superiority. As every other nuclear power except the U.S. modernizes their nuclear weapons, and as the number of nuclear armed states continues to grow, our allies and partners who rely on our extended deterrent are increasingly motivated to consider obtaining their own nuclear arsenal. We must actively pursue a flexible strategy that allays such concerns among allies.

Some assert that a reliable nuclear deterrent does not require the ability to retaliate immediately, only the assurance that U.S. nuclear forces would survive any attack.

Aside from the fact that none of America’s nuclear triad is on “hair-trigger” alert, the reality of fewer nuclear weapons is that we cannot rely solely on a super-survivable second strike nuclear force that deters only by threatening retaliation. Such a posture could readily be perceived as threatening our intent to strike first. We must have a resilient nuclear arsenal that deters a nuclear strike in the first place.

No president would want to ask the American people to ride out a first strike and then trust him to order a retaliatory strike on behalf of the remaining fraction of our population. What the president needs is a nuclear force that would lead no nuclear armed state, faction or terrorist to conclude that it has less to lose by striking us first, even with just one or a few nuclear weapons. We must not give anyone cause to contemplate such a move.

This is a very different form of deterrence than the Cold War. No longer can we rely on the mathematics and purely rational models of nuclear exchange developed in the 20th century. We must understand human perception and decision-making. For 21st century deterrence, the value of first-strike stability is now at least equally important as maintaining an assured retaliation capability. Those of us in the new generation of strategic thinkers have liberated our minds from Cold War thinking to make sure that today, nuclear weapons are never used.

James Blackwell is special advisor to the Air Force’s assistant Chief of Staff for strategic deterrence and nuclear integration.