WASHINGTON — A leaked copy of the Pentagon’s upcoming Nuclear Posture Review calls for the development of a new low-yield warhead for America’s submarines, the creation of a new sub-launched, nuclear-capable cruise missile and a shift in America’s stance on when nuclear weapons may be used.

A draft of the review was posted online Friday by the Huffington Post. The Nuclear Posture Review, or NPR, is scheduled to be formally released in February, and so the document may change somewhat between now and then.

In a statement, the Pentagon did not deny that the draft is authentic, instead saying “Our discussion has been robust and several draft have been written.

“However, the Nuclear Posture Review has not been completed and will ultimately be reviewed and approved by the President and the Secretary of Defense,” the statement read. “As a general practice, we do not discuss pre-decisional, draft copies of strategies and reviews.”

Since his election, President Donald Trump has shown an interest in the nuclear arsenal, complaining it had grown too small and pledging to increase the size and capabilities of America’s nukes — much to the dismay of nonproliferation advocates.

Unsurprisingly, the draft reaffirms the need for a full nuclear triad — the mix of air-, ground- and sea-based nuclear weapons that has formed the backbone of America’s deterrence posture for decades. But the document appears to be in line, at least somewhat, with Trump’s public desires.

Low-yield changes

For months there have been rumors in the nuclear community that the NPR would feature a push to lower-yield nuclear weapons — which already exist on the W80 and B61 nuclear bombs. Based on the draft of the NPR, the Pentagon intends to either modify or create new low-yield nuclear warheads for submarine-launched ballistic missiles, which is not a current capability.

The NPR justifies this as needing to counter the belief among potential adversaries, including Russia, that the U.S. nuclear arsenal is too devastating to ever be used. Offering lower-yield nuclear options, the authors argue, will “enhance deterrence by denying potential adversaries any mistaken confidence that limited nuclear employment can provide a useful advantage over the United States.”

Peter Huessy, a defense consultant who runs his own company, believes the Pentagon is justified in moving in this direction.

“If deterrence is holding at risk what the bad guy values, why is it a bad idea to be able to destroy that military industrial or command authority target as best you can in the most flexible way?” he said. “Otherwise one has to argue any retaliatory use of nuclear weapons of any number or kind has to lead to the use of all weapons and Armageddon... Otherwise you are saying any use by the Russians of one nuclear weapon must require an all-out retaliatory strike by the USA.”

“If an all-out response isn’t credible, then having low-yield, smaller weapons makes sense because it’s a better and more credible deterrent,” Huessy added.

But the nonproliferation community worries that creating lower-yield nuclear weapons, which are still capable of devastating a city, simply increases the inventive to use such weaponry.

Jeffrey Lewis, director of the East Asia Nonproliferation Program at the James Martin Center for Nonproliferation Studies, is more sanguine about the change.

“I don’t think this makes nuclear weapons more usable. On the contrary, I don’t think reducing yield does anything to make our nuclear threats more credible,” he said. “This is a political problem; it does not have a technical solution. So giving the W76 a dual-a-yield option is pointless, not the end of the world.”

Instead, the problem Lewis sees is in the thinking that would lead to the warhead change.

“The theory is that the Russians might do a little nuclear strike and we would want to do a little nuclear strike back,” Lewis said. “The problem is that the reasoning that leads to this proposal and that is found elsewhere in the document about nuclear deterrence is so shoddy that I worry they don’t have very accurate views about the world in which deterrence is supposed to function.”

Cruise missile and policy shifts

In a reversal from the 2010 NPR, under which the U.S. planned to retire its sea-based cruise missile, the Pentagon will pursue a modern, nuclear-armed, submarine-launched cruise missile, or SLCM.

How to get there, however, is an open question. The department is planning an analysis of alternatives for the “rapid development of a modern SLCM,” which Todd Harrison, an analyst with the Center for Strategic and International Studies, thinks needs to be wide-ranging.

“If they do this right, it would be so open as to include everything from modifying Tomahawks, to bringing them back in a nuclear configuration, to modifying the Tomahawk replacement missile that they’d already been working on or developing a custom-designed missile,” Harrison said. “That’s a huge range of costs that you could consider in an AoA.”

For obvious reasons, a new custom-designed weapon would be the most expensive option, but the cost associated with certifying a nuclear weapon means there is no “cheap way” of doing this kind of development, Harrison said.

To avoid a capability gap while that new system is developed, the U.S. will “modify a small number of existing [sub-launched ballistic missile] warheads to provide low-yield options.” The Department of defense and the National Nuclear Security Demonstration, or NNSA, will develop a low-yield SLBM warhead.

Policy shift

From a policy perspective, the NPR is notable for its declaration that nuclear weapons could be deployed in response to “significant non-nuclear strategic attacks,” which could include attacks on the infrastructure, civilian populations, or command and control assets of the U.S. and its allies.

That is a significant departure from previous U.S. stances that nuclear weapons are, essentially, a last resort.

Kingston Reif of the Arms Control Association worries that the language is “dangerously permissive,” given how wide-ranging the definition of a “significant non-nuclear strategic attack” is.

“For example, does Russia’s interference in the 2016 election constitute such an attack?” he asked. “The language is so ambiguous as to be almost meaningless. As such it lacks credibility.”

Speaking Thursday evening, Ernest Moniz, who served as Secretary of Energy from 2013-2017, also raised concerns about the idea that a nuclear response could be used in cases of, say, a cyber attack.

“The entire broadening if the landscape for nuclear deterrence is a very fundamental step in the wrong direction, a really bad one,” Moniz said at an event hosted by the Center for Strategic and Intentional Studies. “I think the idea of nuclear deterrence of cyber attacks, broadly, certainly does not make any sense.”

Cost prohibitive?

The big question hanging over any new technology laid out in the NPR is one of cost.

According to a recent government estimate, the Pentagon is set to spend around $1.2 trillion over the next 30 years to recapitalize the nuclear arsenal, including delivery systems, warheads and modernization. And those costs are going to eat into the Pentagon’s overall budget at a time when a large number of defense modernization projects are also coming due.

Funding for a new low-yield warhead would run through the Department of Energy’s budget, as warhead programs are managed by the NNSA. But those funds are still restricted under the budget caps, which means the money would need to come from the overall defense pot.

So how much could a new warhead design, or even just a modification of an existing system, cost? That’s where it gets tricky.”

In 2016, the Pentagon’s office of Cost Assessment and Program Evaluation was trying to find a solid cost estimate for designing and building the Air Force’s new intercontinental ballistic missile design. But researchers found it was almost impossible to nail down a hard number because it had been so long since America designed something similar.

Harrison believes the same challenge applies for a new warhead design.

“I don’t think you can come up with a cost estimate that you can have much confidence in, period. It’s been so long since we did it,” he said. “So that’s going to be an unknown cost for quite a while. There is tremendous uncertainty in the cost estimate for this new warhead.”

Which maybe the best way to sum up this draft of the NPR ― policy shift aside, it is unclear how much of it would get paid for.

“It is a wish list with a healthy dose of propaganda,” Lewis said of the overall document. “But a wish list can’t implement itself, and simply asserting it’s affordable doesn’t make it so.”

Aaron Mehta was deputy editor and senior Pentagon correspondent for Defense News, covering policy, strategy and acquisition at the highest levels of the Defense Department and its international partners.

More In Nuclear Triad