"It's not an arms race in terms of numbers like during the Cold War, but is an arms race that involves more than just the United States and Russian Federation and it involves upgrading and improving the capability of existing nuclear forces", Reif said.
In words of Secretary of Defense James Mattis, "America can afford survival".
"China, too, is modernizing and expanding its already considerable nuclear forces", the NPR said.
The review comes at a critical moment in the nation's history, Defense Secretary James N. Mattis wrote in the preface of the NPR, adding "America confronts an global security situation that is more complex and demanding than any since the end of the Cold War".
"We must look reality in the eye and see the world as it is, not as we wish it to be", the NPR said, "given the range of potential adversaries, their capabilities and strategic objectives". "This NPR responds to today's security needs with a tailored nuclear deterrent strategy". They are created to deter large-scale attacks on the United States or allies.
The new Pentagon policy also outlines longer-term plans to reintroduce a nuclear submarine-launched cruise missile called an SLCM ("slick-em"), which the administration of President George H.W. Bush stopped deploying and the Obama administration ordered removed from the stockpile.
"Neither recommendation requires developing new nuclear warheads", Shanahan said. The recommendations align with nonproliferation commitments and strengthen American deterrence, he said.
The review clarifies the USA will use nuclear weapons only in "extreme circumstances", but those circumstances could include "significant non-nuclear strategic attacks".
Moscow has condemned United States military proposals to develop new, smaller atomic bombs mainly to deter any Russian use of nuclear weapons.
Critics say the new stance will increase the chance of a miscalculation between the pair, with Russia's response unlikely to dampen such thoughts.
The Pentagon denies those accusations, pointing out that the new policy continues to stipulate that the United States would only ever use nuclear weapons in "extreme circumstances".
Kono said Japan, which relies on the USA nuclear umbrella, "shares with the United States the same recognition of such a severe security environment".
"In a broader context, Russian Federation is either rejecting or avoiding its obligations and commitments under numerous agreements, and has rebuffed US efforts to follow the New Strategic Arms Reduction Treaty (START) with another round of negotiated reductions and to pursue reductions in non-strategic nuclear forces", it added. About $34 billion was slated to replace aging submarine-based weapons, intercontinental missiles, cruise missiles, bombers and bombs.