Do we really need yet another type of nuclear weapon?

This year’s Defense Authorization Act mandates creation of “a program for the development of a nuclear-armed, sea-launched cruise missile (SLCM-N) capability.” The new weapon would be placed on attack submarines and, maybe later, on warships. The directive caps a decades-long effort by a group of nuclear enthusiasts, working through Congress, to replace the older SLCM-Ns that were retired by President George H.W. Bush in 1991.

Building a new missile is a partisan issue. President Obama got rid of the old SLCM-Ns, which had been stored in a warehouse in upstate New York for 10 years, and rejected a new version. President Trump installed a new program, then President Biden killed it.

In April, the Defense Department decided what constitutes the mandated SLCM-N capability, meaning how to structure the program and how much money to request for it. The still-secret decisions are unlikely to satisfy the new weapon’s backers, however, and the issue will thus return to Capitol Hill.

Whatever is decided will ultimately add to the already $2 trillion (yes, that’s a T) nuclear modernization program. In 2016, the Congressional Budget Office estimated that nuclear modernization would cost $1.4 trillion over the next 30 years. Since then, real costs have risen in just about every component of the plan, to say nothing of inflation. It will divert funds and technological talent that otherwise might be spent on the Navy’s conventional forces — the warships and submarines and aircraft that defend U.S. interests every day.

Greater attention to nukes also diverts planners from the advanced technologies that now dominate armed conflicts at sea, as has been shown by the ability of Ukrainian drones to destroy much of Russia’s Black Sea fleet. More importantly, it gives the lie to decades-long American efforts to constrain the roles of nuclear weapons in our and other nations’ military planning.

So why would anyone support such folly? Last year, the congressional Strategic Posture Commission argued that the U.S. needed “theater nuclear forces deployed or based in the Asia-Pacific theater…to deter or counter Chinese or Russian limited nuclear use in theater.” The commission claimed that in the event of war with China or North Korea, deterring use of nuclear weapons in the Pacific requires a capability to respond from the Pacific.

Further, they argued, Japan and other nations will doubt our security guarantees in the absence of such a capability. They argued that the threat of nuclear-armed intercontinental missiles based in four U.S. states would not be sufficient. As for our nuclear-armed ballistic missile submarines, now being modernized, that already patrol in the Pacific, one supporter says that more options for delivering a response would permit the U.S. to be more flexible in negotiating. Huh?

Moreover, the U.S. already has air-launched nuclear-armed cruise missiles that also are being modernized and will be delivered by the new B-21 bomber, as well as by older bombers. In fact, current bombers already deploy periodically to Guam and conduct flights near China and North Korea to remind them of our capabilities. SLCM-N supporters maintain we cannot be certain that bombers will be able to penetrate future Chinese air defenses. Then why are we planning to spend about $70 billion to buy 100 of them?

The main point is that all the arguments are based on nothing. Nuclear deterrence theory — and it’s all theory, not laws of nature — is made up. The “Wizards of Armageddon,” a group of theoreticians at the Air Force’s RAND Corporation, made up nuclear deterrence theory following the first wartime uses of Oppenheimer’s bomb. Their ideas have been massaged and expanded and extrapolated ever since. There’s no science behind this; it’s speculation.

To deter a nation from taking a certain action requires convincing a specific decision-maker that the costs of the action will exceed the value of whatever he or she perceives to be at stake. Costs are anything valued by the decision-maker — both national and personal. No one knows who China’s or North Korea’s decision-maker might be at the time of a future crisis, and nor what he or she might value.

Nor can we be sure what that person would know about the state of play. Would he or she be a risk-taker or cautious? Would he or she prioritize national interests or, like Saddam Hussein during the 1990 Gulf War, put personal interests first? Would Kim Jong Un care whether a nuclear strike came from the Pacific or elsewhere, from an aircraft or a submarine, whether the missile was ballistic or cruise? Indeed, would Kim know from where or from what platform a nuclear blast originated? Studies of past nuclear crises emphasize the limited information, confusion and contradictory pressures that dominate decisions. Given the disruption of communications and surveillance systems that would accompany nuclear explosions, confusion is guaranteed.

There is one more reason to object. A central element in President Biden’s foreign policy has been strengthening the U.S. military posture in the Indo-Pacific region, a key component of which is the Australia-UK-US Enhanced Security Partnership (AUKUS). But Australia is hesitant about nuclear weapons. It is party to the Treaty of Rarotonga, which prohibits basing nuclear weapons in the South Pacific. When the public became aware in the 1980s that some U.S. warships carried nuclear weapons, New Zealand — another Rarotonga signatory — banned all American warships from its ports. If even some U.S. attack submarines are armed with SLCM-Ns, no subs will be permitted to base Down Under.

In addition, the first step in fulfilling the new partnership was Australia’s agreement to purchase nuclear-powered attack submarines from its partners. The deal is controversial, with some Australian politicians seeing the agreement as a step toward nuclear proliferation. Equipping U.S. submarines with SLCM-Ns will empower this position and could jeopardize the new arrangement.

In short, there is no good reason for developing SLCM-Ns, but significant reasons to oppose them: cost, damage to efforts to discourage other nations’ reliance on nuclear weapons and potential to aggravate U.S.-Australia ties. There are more than enough projects already on the nuclear modernization agenda — don’t complicate it further!

Barry Blechman is a former State Department official and co-founder of the Stimson Center. He has worked on defense issues for 60 years in government and in private organizations.