The Trump administration’s new, revised nuclear weapons policy squarely targets Russia’s growing stockpile of non-strategic nuclear weapons with a more forceful doctrine and new low-yield warheads designed to send Moscow a message.

While much of the Trump Nuclear Posture Review released Friday is a word-for-word continuation of former President Barack Obama’s 2010 review, there are some notable differences that the Pentagon says are designed to enhance deterrence, not increase the chances of nuclear war.

That includes a recommendation to lower the yield of some existing submarine-launched ballistic-missile warheads, and bring back a nuclear sea-launched cruise missile, a capability the U.S. had during the Cold War.

“Neither recommendation requires developing new nuclear warheads. Neither will increase the size of our nuclear stockpile. They break no treaty,” said Deputy Defense Secretary Pat Shanahan at a Pentagon briefing Friday.

“They align with our non-proliferation commitments. They strengthen American deterrence,” Shanahan said.

The new “supplements” are also aimed directly at Moscow, and its espoused national security doctrine known as “escalate to deescalate.” It's the belief that threatening, or even carrying out, a limited nuclear strike would paralyze the U.S. and NATO because the West lacks any credible limited response.

Russia has a large numerical superiority in tactical nuclear weapons that in some cases are not limited by treaty because they are not delivered by long-range intercontinental ballistic missiles.

They include roughly 2,000 “non-strategic” weapons such as air-to-surface missiles, gravity bombs, depth charges, short-range ballistic missiles, ground, air, and sea-launched cruise missiles, anti-aircraft missiles, and torpedoes for surface ships and submarines, according to Robert Soofer, deputy assistant secretary of defense for nuclear and missile defense policy.

“Why are they building a nuclear depth charge? Why are they building nuclear torpedoes?” Soofer asked. “They think that they can use this.”

The addition of low-yield warheads that can be fired from ballistic missile submarines deep in the ocean is designed as a counterbalance to prevent a miscalculation in Moscow, Pentagon officials say.

“Russia must instead understand that nuclear first-use, however limited, will fail to achieve its objectives, fundamentally alter the nature of a conflict, and trigger incalculable and intolerable costs for Moscow,” the review said. “This strategy will ensure Russia understands it has no advantages in will, non-nuclear capabilities, or nuclear escalation options. Correcting any Russian misperceptions along these lines is important to maintaining deterrence in Europe and strategic stability.”

The whole point of adding the low-yield option is not to make it easier for the U.S. to use nuclear weapons in a first strike, but rather to make it harder for the Russians, says Greg Weaver, a strategic planner for the Joint Chiefs of Staff.

“These additional capabilities will make a U.S. nuclear response to Russian limited use more credible, raising the Russian nuclear threshold, not lowering ours,” Weaver said in a briefing for reporters at the Pentagon.

The U.S. would also like to motivate Russia to return to arms talks that would result in deeper cuts in U.S. and Russian nuclear arsenals.

After the 2010 New Strategic Arms Reduction Treaty, which limited each side to 1,550 deployed strategic nuclear warheads, the Russians have shown no interest in further arms reductions. In fact, according to the U.S., Russia has violated the Intermediate-Range Nuclear Forces Treaty by deploying ground-based cruise missiles.

The recommendation to add submarine-launched cruise missiles (SLCM), which would take seven to 10 years to design and build, is basically a bargaining chip, Pentagon officials admit

“Were Russia to agree to return to verifiable arms control measures to address the imbalance in nonstrategic nuclear forces, the U.S. might agree to limit or forgo acquiring a nuclear SLCM,” Soofer said.

But pursuing non-proliferation must be done from a “position of persuasion,” Defense Secretary Jim Mattis told Pentagon reporters just before the release of the NPR. “What we are trying to do is ensure that our diplomats and our negotiators are in a position to be listened to when we say we want to go forward on non-proliferation and arms control,” Mattis said.

Another difference from the Obama NPR is the tone of the document.

Gone is language touting the declining role of nuclear weapons in responding to non-nuclear attacks, and promises to continue to reduce the role of nuclear weapons in non-nuclear scenarios.

The Trump NPR contains no such language.

But Pentagon officials insist the change is more of emphasis and doesn’t expand the range of circumstances under which nuclear weapons would be used.

“The United States would only consider the employment of nuclear weapons in extreme circumstances to defend the vital interests of the United States, its allies, and partners,” reads the Trump NPR, language nearly identical to the previous version.

It does, however, say U.S. nuclear capabilities will remain a hedge against multiple potential risks, including chemical, biological, cyber and large-scale conventional aggression.

“If you go back to the 2010 NPR and read it very carefully there is no circumstance under which the Obama administration ruled out the willingness of the United States to use a nuclear weapon in response if it was in extreme circumstances in defense of vital interest,” Weaver said. “They didn’t rule out anything, and neither do we. There is no intent to expand the range of circumstances. It does not do that.”

In 2010, the non-nuclear threats listed in the NPR included conventional, biological or chemical. No mention was made of cyber because it wasn’t perceived to be as great a threat as it is today.

“The NPR clarifies longstanding policy that 'extreme circumstances' could include significant non-nuclear strategic attacks,” Shanahan said. “This clarification is stabilizing. It lowers the risk of nuclear use by anyone.”