According to Buzhinsky, the United States needs tactical nuclear weapons "not to defend its national security and its territory but to use them at a distant theater of operations in the name of defending its interests or interests of its partners and allies".
"The idea is, once again, to keep our negotiators negotiating from a position of strength", Mattis told a House Armed Services Committee hearing on the administration's Nuclear Posture Review, which was released last week.
Although the review largely focuses on Russian Federation, several sections are dedicated to the lack of transparency in China's nuclear build-up.
The document said the U.S. will develop for deployment a "low-yield" nuclear warhead for submarine-launched ballistic missiles.
In a statement, the Union of Concerned Scientists said the NPR misrepresented China's nuclear power. Berlin does not have its own arsenal, but the Pentagon maintained nuclear warheads in Germany as part of a big military presence created to deter Soviet invasion of western Europe.
"In order to meet the central limits of the treaty, the United States developed and utilized conversion procedures in full compliance with its treaty obligations", it said.
Since taking office in 2012 President Xi Jinping has pushed for a muscular China, including calls last October to develop a "world-class" military by 2050.
We hope that this trend continues and that the U.S. will no longer see the need to further boost its already top nuclear capability, lest this spur traditional Cold War rival Russian Federation to respond and trigger a new worldwide arms race.
China responded to this with a pledge that it will never be first to use nuclear weapons "under any circumstances".
"If you believe that nuclear weapons deter and bring peace and stability, then we should welcome North Korea", Beatrice Fihn, executive director of the International Campaign to Abolish Nuclear Weapons, said mockingly.
Earlier in January, the US president waived a series of sanctions against Iran as required under the JCPOA, but warned the European allies and the US Congress that it will be the last such waiver he signs if they fail to agree to radical changes to the nuclear deal.
Moscow denounced what it called the "bellicose" and "anti-Russian" nature of the new U.S. nuclear policy, warning that it would take the necessary measures to ensure its own security.
Russian Federation saw the USA document as confrontational, and governments around the world raised fears that it could increase the risk of miscalculation between the two world powers.
Iran accused the US on Sunday of threatening Russian Federation with new atomic weapons after Washington published a document on Friday outlining plans to expand its nuclear capabilities to deter others.
Only one country has ever used nuclear weapons against another country.
The document first came under fire from Iranian Foreign Minister Mohammad Javad Zarif on Saturday, when he tweeted that the U.S. policy document posed the risk of "bringing humankind closer to annihilation." .
"Mr Zarif also said in his tweet: "(U.S. President Donald) Trump's obduracy in killing the #JCPOA (Iran's nuclear deal with world powers) stems from the same unsafe imprudence".
It is the first time since 2010 that the USA military has enunciated how it foresees nuclear threats in the coming decades.
Iran's nuclear deal, reached with six world powers, lifted some global sanctions in exchange for curbs to its nuclear programme.