Defense officials say having those smaller nuclear weapons is now a necessary deterrence.
What's more, attribution is a really hard subject when it comes to cyber attacks - do you really want to lob an ICBM at another country thinking they carried out an attack when you can't be sure?
In reality, the review is a balanced document carefully weighing the impact of unsafe worldwide trends like a resurgent Russian Federation and an aggressive China on US nuclear posture.
The administration proposes a two-step solution.
The review suggests a hawkish approach to cooperation with Russian Federation over nuclear proliferation.
The Nuclear Posture Review makes the case for the continued importance of nuclear triad for deterring aggression and preserving peace.
The lower-yield warhead for Trident missiles would "ensure a prompt response option" and would help counter any "mistaken perception" by Russia, North Korea or other adversaries that the USA might hesitate to respond with nuclear weapons to a limited nuclear strike by one of them, the report said.
According to the report, the USA will work to increase transparency and predictability to avoid potential miscalculation among nuclear weapons states and other possessor states.
Pakistan has repeatedly denied such fears and asserted that its nuclear arsenals are one of the safest and secure ones in the world. That world was much less pleasant than the relative peace and stability since the dawn of the nuclear age.
However, Shanahan said that the NPR also "clarifies" the long-standing policy to state that "extreme circumstances" could include "significant non-nuclear strategic attacks" that would bring about a USA nuclear response. They are created to deter large-scale attacks on the United States or allies.
The lower-yield weapons would enhance the credibility of the USA arsenal, the review claims.
Jon B.Wolfsthal, a former USA government official now leading the Nuclear Crisis Group, pointed out that the NPR had a bit of an exceptionalism problem.
It calls for the introduction of "low-yield nukes" on submarine-launched ballistic missiles, and the resumption of the nuclear-submarine-launched cruise missile (SLC-M) whose production stopped during the George W. Bush era and which Obama removed from the nuclear arsenal.More news: Why this cricket match is under investigation
The review called for continuing the B-83 bomb, the largest nuclear weapon in the U.S. stockpile, until a replacement is found, reversing plans to retire it.
Anyone who has been feeling nostalgic for the 1970s and 80s will have had their flare and electronica-filled dreams rudely interrupted this month by a less welcome visitor from the past - the threat of nuclear war.
"Recent Russian statements on this evolving nuclear weapons doctrine appear to lower the threshold for Moscow's first-use of nuclear weapons", the review said.
The nuclear posture also outlines the unprecedented use of nuclear weapons in response to a nonnuclear attack and emphasizes the potential use of "low-yield" nuclear weapons, which the administration says would provide a different range and would improve readiness and "survivability".
The strategy would challenge the view that USA nuclear weapons are too big to be used and therefore no longer an effective deterrent.
USA officials have in the past expressed concern over the possibility of nuclear weapons of Pakistan landing into the hands of non-state actors or terrorist groups and thus has been working with Islamabad in enhancing the security of its nuclear weapons.
A key shift from existing nuclear weapons policy is the expansion of scenarios in which a nuclear threats would be considered.
Underlining the policy is the idea that a nuclear exchange between the United States and Russian Federation could be limited to the least destructive weapons in both countries' nuclear stockpiles.
Nuclear attacks, by contrast, are created to inflict the greatest amount of damage as possible, which also means killing as many people as possible. It communicates to adversaries that the U.S.is willing to contemplate the use of the most devastating weapons it has at its disposal in response to large-scale attacks, regardless of how those attacks are conducted. USA delivery platforms modernization and warhead recapitalization will cost about 6.4 percent at their peaks, or less than 1 percent of the federal budget.
"No football team only plays defense", Mattis said.
The U.S. now has roughly 1,400 nuclear weapons, down from a high of more than 12,000 during the 1980s.
The nation and allies will require their stabilizing effects for decades to come.
The Pentagon released its new nuclear weapons strategy on Friday afternoon, announcing that two new types of weapons will be made and effectively reversing the Obama administration's policy to reduce America's nuclear arsenal and de-emphasize nuclear warfare as a defense strategy.