Concerns have been raised overDonald Trump's administration plans to develop smaller yield nuclear weapons and lessen constraints on the usage of such weapons in warfare.

Sources speaking to The Japan Times and The Guardian both outline how the Nuclear Posture Review, to be published later in January, is much more hawkish than previous administrations and aimed to strength the position of the US's military might against adversaries such as Russia, China, and North Korea.

According to the Guardian, the new review would add scenarios where the US would be justified in using nuclear weapons to include responding to attacks with mass casualties and targeting the nuclear facilities of other countries.

The suggested development of smaller yield nuclear weapons has worried some that it increases the likelihood of the devastating weapons being used.

One former official who said they had seen what the believed to be the final draft of the review, told the Guardian that it came back from extreme earlier edition but was "still bad."

The last Nuclear Posture Review was released in May 2010 under former president Barack Obama and focused more on reducing the role of nuclear weapons and heightening transparency around the stockpile in the US, thereby reducing the risks of nuclear weapons in the world.

Secretary of defence at the time of the last review, Robert Gates, said then: "The NPR provides a road map for implementing President Obama's agenda for reducing nuclear risks to the United States, our allies and partners and the international community.

"This review describes how the United States will reduce the role and numbers of nuclear weapons with a long-term goal of a nuclear-free world."

Then US Secretary of State Hillary Clinton said the review recalibrated priorities "to prevent nuclear proliferation and nuclear terrorism", adding: "we are reducing the role and number of weapons in our arsenal, while maintaining a safe, secure and effective deterrent to protect our nation, allies and partners."