The proposed changes to the nuclear weapons program, outlined in a draft version of the Pentagon's Nuclear Posture Review, mark a significant break from the vision for America's nuclear future under Barack Obama, who during a famous speech in Prague in 2009 called for the elimination of nuclear weapons.
Arguing today's security environment is vastly more complex than in 2010 -- the last time the Pentagon published a nuclear review -- the draft document states that the US needs to realign its nuclear policy with a "realistic assessment" of the threats it now faces, including from North Korea, Russia and China.
"Global threat conditions have worsened markedly" since the 2010 nuclear policy review, Defense Secretary Jim Mattis wrote in the document's introduction, a leaked version of which was published by the Huffington Post.
"The United States now faces a more diverse and advanced nuclear-threat environment than ever before."
The new strategy calls for a continuation of the nuclear modernization program ordered by Obama, but notable changes include a call for the increased development of low-yield nuclear weapons.
These devices, also known as "tactical" nukes, are still extremely powerful and can pack as much destructive punch as the bombs dropped on Hiroshima and Nagasaki at the end of World War II.
Policymakers worry that regular, large-yield weapons are essentially too big to ever be detonated, as their use would likely result in large-scale retaliation from an adversary and wipe too much of humanity off the map.
The Pentagon argues that by having more, smaller nukes it will counter adversaries' "mistaken confidence" that the United States would not respond to another country using its own low-yield bomb.
"Expanding flexible US nuclear options now, to include low-yield options, is important for the preservation of credible deterrence against regional aggression," the document states.
The proposed policy says the Defense Department and the National Nuclear Security Administration will develop a low-yield submarine-launched ballistic missile for deployment.
Such a capability would ensure "a prompt response option that is able to penetrate adversary defenses."
Barry Blechman, co-founder of the Stimson Center, a nonpartisan anti-nuclear proliferation think tank in Washington, warned that the review contains major steps backward from the goals of previous administrations -- to reduce the risk of nuclear war and prevent nuclear weapons spreading to additional nations.
"Nuclear ideologues maintain that the US has to match the adversary's arsenal, weapon for weapon, yield for yield, to deter nuclear use," Blechman said in a statement to AFP.
"There is no empirical basis for this view, but it is widely held among civilians being appointed to positions in the" administration of President Donald Trump.
As president-elect in December 2016, Trump called for the United States to "greatly strengthen and expand" its nuclear capabilities -- and within days of entering office he called for a new nuclear policy.
The nuclear review states that the development of new, lower-yield nuclear weapons is not intended to enable "nuclear war-fighting" that would see the US military using the weapons on the battlefield.
The Pentagon declined to comment on the policy review, saying it remained "pre-decisional" and not approved by Trump. The final version is due for release February 2.
The document also states that Russia is upgrading its nuclear "triad" of air-, sea- and land-based missiles to include a new "hypersonic glide vehicle" and a new intercontinental, nuclear-armed, undersea autonomous torpedo.
The New York Times reported Wednesday that the policy review also outlines changes to the threshold at which America could respond with nuclear weapons -- including a massive cyber attack.
The document states that the United States would only consider using nuclear weapons in "extreme circumstances."
These include "attacks on the US, allied, or partner civilian population or infrastructure, their command and control, or warning and attack assessment capabilities," the document states.
Blechman said this goes against the spirit of the 1968 global non-proliferation treaty aimed at curtailing the spread of nuclear weapons.
"It would encourage those in many other countries who argue that nuclear weapons are essential to security," he said.
The nuclear review states its commitment to the non-proliferation treaty "remains strong."
But, it goes on, "the current environment makes further progress toward nuclear arms reductions in the near term extremely challenging."
Michaela Dodge, a senior policy analyst at the Heritage Foundation think tank, disputed critics' contention that the new policy could lead to more conflict, or that it would break the spirit of the non-proliferation treaty.
"Additionally, a decision to use nuclear weapons would not be made haphazardly," she told AFP.
The nuclear posture review "process is run by serious people with in-depth understanding of difficult nuclear weapons policy challenges."
(Except for the headline, this story has not been edited by NDTV staff and is published from a syndicated feed.)