Since the 1970s, in fits and starts, U.S. policy has been to reduce nuclear arsenals, its own, and the rest of the world’s. Even Ronald Reagan—who notoriously joked to radio technicians preparing him for a campaign speech on NPR in 1984 that “My fellow Americans, I'm pleased to tell you today that I've signed legislation that will outlaw Russia forever. We begin bombing in five minutes”—chose to work with Soviet leader Mikhail Gorbachev for mutual cuts in the nuclear stockpiles of both the U.S. and U.S.S.R. Further cuts were made under subsequent administrations. No more.

The majority of the Russian and U.S. nuclear arsenals are held in “active reserve” and would take considerable time to bring back to operational status. But together, they have about 3,500 nuclear warheads actively deployed and ready for action in minutes.

As noted here last month, Trump has ordered new, lower-yield warheads, including one that can be loaded onto cruise missiles, which have only carried conventional explosives since 2010. These tactical weapons aren’t city-busters like so many of the warheads now in the U.S. arsenal, but mini-nukes for use against targets like a nuclear processing complex, a biological weapons factory, or advancing troops in the field.

The fact they are of lesser yield makes nuclear war more likely.

The problem from the military planners’ point of view, warhawks have said for decades, is that the bigger bombs in our arsenal—some of them with 30 times the explosive force of the Hiroshima bomb—are so destructive that commanders fear using them. They know what the consequences of a full-scale “nuclear exchange” would be: a blasting away of civilization followed by nuclear winter encompassing the whole Northern Hemisphere.

But mini-nukes? Having those at hand might make commanders less hesitant about launching them. Not only would the use of nuclear weapons be made more palatable to politicians and commanders, the excuses for using them would change. Hennigan again:

Trump’s new plan also expands the President’s “first use” of nuclear weapons to circumstances that include “non-nuclear strategic attacks” against the U.S. or its allies. That could mean cyberattacks on nuclear command and control systems or civilian infrastructure, like the electricity grid or air-traffic-control system, arms-control experts have concluded. Previous Administrations limited the threat of a nuclear response to mass-casualty events, like chemical- and biological-weapon attacks. Stephen Schwartz, a nuclear weapons policy expert, said the key concern is the expansion of the nuclear umbrella to “include these new and not extreme possibilities, thus dramatically lowering the threshold for nuclear use.”

Our leaders talk about such scenarios in terms of “limited nuclear war,” a conceit that is stunning in its reckless idiocy. It doesn’t take much thought or delving into the history of warfare to know that limiting a war once it gets started is far from a sure thing even when the only weapons are conventional. When the bombs start falling, the diplomats retreat to the bunkers like everyone else. First the low-yield tactical nukes fly, and on their heels come the civilization wasters.

The new policies are being concretized in the latest Nuclear Posture Review, which has not been finalized, but soon will be. Last month, Ashley Feinberg at The Huffington Post scrutinized a “pre-decisional” copy of the NPR here.

In his State of the Union address Tuesday, Trump said, “We must modernize and rebuild our nuclear arsenal, hopefully never having to use it, but making it so strong and powerful that it will deter any acts of aggression.”

But that arsenal is already massive, 1,740 ready-to-use nukes on land- and sea-based missiles, as well as gravity weapons carried by airplanes. Plus thousands more warheads in reserve. The Russians have similar numbers. Anyone undeterred by that is not going to be deterred by more.

A few months ago, James Doyle at the Bulletin for Atomic Scientists wrote:

In December [2016], the Defense Science Board—an independent group of experts and former officials that provides advice to the Defense Department—submitted a report advising the Pentagon to invest in low-yield nuclear weapons that could provide “a rapid, tailored nuclear option for limited use.” This recommendation struck a familiar note. In 2003, the board issued a study entitled “Future Strategic Strike Forces” that suggested building small nuclear weapons with “great precision, deep penetration, [and] greatly reduced” yield and radioactivity. The board’s call led to investments in new warhead designs such as the Robust Nuclear Earth Penetrator—a warhead designed to destroy deeply buried or hardened targets including underground military command centers—and the Reliable Replacement Warhead. Both programs were cancelled in 2008, after millions of dollars had been spent. Despite the board’s renewed interest in smaller nuclear weapons, and in weapons tailored for limited uses or specific effects, any effort to develop these weapons would encounter the same problem that earlier such efforts have encountered: It is impossible to determine if introducing weapons with these characteristics into the US stockpile, and planning for their use in certain scenarios, would strengthen deterrence or make nuclear war by miscalculation more likely. Building “mini” or tailored nuclear weapons might well lower the threshold to nuclear war; risking that outcome would only make sense if it were absolutely clear that introducing these weapons would remedy some dangerous weakness in deterrence. Fortunately, no such weakness exists. Any nation using nuclear weapons against the United States or its allies risks a devastating response whose negative consequences would far outweigh any gains delivered by crossing the nuclear threshold.

Bryan Bender at Politico wrote last September:

"It is difficult to imagine the circumstances under which we would need a military option in between our formidable conventional capabilities and our current low-yield nuclear weapons capabilities," added Alexandra Bell, a former State Department arms control official. "Lawmakers should be very wary of any attempt to reduce the threshold for nuclear use. There is no such thing as a minor nuclear war."

There is a much-ignored part of the Nuclear Non-Proliferation Treaty—Article VI:

Each of the Parties to the Treaty undertakes to pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control.

That should have been item No. 1 on the minds of the drafters of the latest Nuclear Posture Review, not the development and building of more nuclear weapons, no matter how mini or many.