"Expanding flexible U.S. nuclear options now, to include low-yield options, is important for the preservation of credible deterrence against regional aggression," states the Pentagon's Nuclear Posture Review. | Getty Images Trump plan calls for new nuclear weapons

The Trump administration on Friday called for the development of two new types of nuclear weapons to better deter potential adversaries, in a reassessment of the current arsenal that critics slammed as increasing the likelihood of nuclear conflict.

The Pentagon's Nuclear Posture Review, the first since 2010, calls for a "lower-yield" option — with less powerful explosive capacity — for ballistic and cruise missiles launched from submarines.


It also says that nuclear weapons could be used to respond to “extreme circumstances,” including non-nuclear attacks.

The new steps are needed to respond to aggressive efforts by Russia and China to update their arsenals, as well as nuclear provocations from North Korea and the ambiguity surrounding Iran’s ambitions, Defense Secretary Jim Mattis wrote in the unclassified summary of the secret review.

“We must look reality in the eye and see the world as it is, not as we wish it to be,” Mattis says, stressing that “in no way does this approach lower the nuclear threshold.”

The lower-yield weapons would enhance the credibility of the U.S. arsenal, the review asserts.

"Expanding flexible U.S. nuclear options now, to include low-yield options, is important for the preservation of credible deterrence against regional aggression," the 10-page summary states.

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They could also be used to deter large-scale non-nuclear attacks.

"These supplements to the planned nuclear force replacement program are prudent options for enhancing the flexibility and diversity of U.S. nuclear capabilities," the review says. "They are compliant with all treaties and agreements, and together, they will: provide a diverse set of characteristics enhancing our ability to tailor deterrence and assurance; expand the range of credible U.S. options for responding to nuclear or non-nuclear strategic attack; and, enhance deterrence by signaling to potential adversaries that their limited nuclear escalation offers no exploitable advantage."

But arms control advocates caution that broadening the set of circumstances when the U.S. might use nuclear weapons runs the risk of increasing the likelihood of a nuclear conflict.

“This is a very dangerous sort of slide where we start to soften up the norm with [respect] to nuclear weapons,” said Beatrice Fihn, director of the International Campaign to Abolish Nuclear Weapons. “It makes the likelihood of use accidentally or on purpose much more likely.”

Deputy Defense Secretary Pat Shanahan on Friday disputed that argument, which has been widely expressed since a draft of the document leaked last month.

At the Pentagon on Friday he argued that the review is a continuation of what U.S. nuclear policy has been since the Cold War.

“Some will say that any additional capability, no matter how measured, increases the chances of using on of these weapons,” Shanahan told reporters. “On the contrary, it is the exact opposite.”

Developing lower-yield nuclear weapons allows the U.S. to avoid the “limits” of a “one-size-fits-all” policy and does not grow the nuclear stockpile or break any treaty obligations, Shanahan said. And clarifying “longstanding policy” that nuclear weapons could be used to respond to a severe non-nuclear attack is “stabilizing.”

“It lowers the risk of nuclear use by anyone,” he said. “The United States does not want to use nuclear weapons.”

John Rood, the undersecretary of Defense for policy, said the military is looking to spend "a modest amount" on the lower-yield ballistic missile "in the near term" — beginning in the administration's fiscal 2019 budget request later this month.

The Department of Energy builds the nation's nuclear warheads.

Reviving the submarine-launched cruise missile, meanwhile, appears to be a longer-term plan. Rood said a study needs to be completed on the cost and timeline.

Supporters say the plan fills a gap in nuclear capability that leaves the U.S. vulnerable.

Michaela Dodge, a senior policy analyst at the Heritage Foundation, said Russia believes the U.S. will not use one of its high-yield nuclear weapons to respond to a low-yield attack, so having a lower-yield option increases deterrence.

“In their minds, they are more likely to think they can get away with using low-yield nuclear weapons in certain scenarios, like when they’re losing with conventional weapons,” Dodge said.

But opponents argue that the strategy marks a dramatic departure from previous policy set by the Obama administration’s 2010 Nuclear Posture Review.

In addition to the two new proposed weapons — including replacing the nuclear-armed Tomahawk cruise missiles that were retired in 2013 — the assertion that that nuclear weapons could be used to respond to “extreme circumstances" short of a nuclear attack was particularly concerning.

“The 2010 review sought to narrow the roles and missions for nuclear weapons in U.S. strategy. This one very explicitly seeks to broaden the roles and the missions,” said Daryl Kimball, executive director of the Arms Control Association. “It very explicitly says that nuclear weapons have a role beyond deterring nuclear use, that they have a role in countering non-nuclear strategic threats too.”

Being willing to use nuclear weapons to respond to something like a massive cyberattack also increases the risk of a significant “blunder,” Ernest Moniz, a former Energy secretary under Obama, and former Sen. Sam Nunn, a co-chair of the Nuclear Threat Initiative, wrote in an op-ed Thursday.

“If a cyberattack took out a major part of our electrical grid, would we be able to quickly and confidently identify the attacking country?” the men wrote.

Critics also allege that the plan to bring new weapons into the U.S. nuclear arsenal will launch a global nuclear arms race, prompting countries like Russia and China to rush to further expand their nuclear power in response.

“It will reinforce the existing trends in their programs to expand their capabilities to counter what they fear to be a widening array of U.S. nuclear threats,” Kimball said. “Just because Russia may have low-yield nuclear warhead options doesn’t mean we need to make the same dumb mistake.”

The Trump administration review also continues the Obama administration’s $1.2 trillion plan to modernize each leg of the nuclear triad: nuclear-armed bombers, submarines and land-based intercontinental ballistic missiles.

It is an investment that some in Congress say is already too high, even without any new classes of weapons.

"This Nuclear Posture Review takes the United States in a dangerous direction that will undermine our defense posture, and further aggravate our national security budgeting difficulties," Rep. Adam Smith of Washington, the top Democrat on the House Armed Services Committee, said in a statement Friday. “The U.S. Congress is currently unable to fund the existing, unrealistic $1.2 trillion plan to upgrade our nuclear weapons enterprise. By requesting even more new nuclear weapon systems and additional unneeded capacity, President [Donald] Trump is making the problem worse."

But key Republicans who applauded the plan said it is essential that Congress find the money.

Sen. John McCain (R-Ariz.), chairman of the Senate Armed Services Committee, promised in a statement to work to provide "sustained funding" — a sentiment echoed by Rep. Mac Thornberry (R-Texas), his counterpart in the House.

"The programs that support our deterrent, from nuclear plants and labs, new ballistic missile submarines, a modern bomber program, and our ICBMs, are already broadly supported in Congress and by the American people," Thornberry said in a statement. "Like other national security programs, they depend on adequate and reliable funding from Congress."

