The warning comes in a statement released by the Union of Concerned Scientists, and follows the White House’s decision to release its Nuclear Posture Review (NPR).
Lisbeth Gronlund, of the Union of Concerned Scientists, said: “One of the most disturbing and significant changes to US policy outlined in the NPR is the tighter integration of US nuclear and conventional forces, including training and exercising with these integrated forces, so US forces can operate— as the NPR states —in the face of nuclear threats and employment.
“This is the text-book definition of nuclear war-fighting. This new policy deliberately blurs the line between nuclear and conventional forces and eliminates a clear firewall.”
According to the NPR, the US military has proposed diversifying its nuclear arsenal.
It has also proposed the development of new, smaller atomic bombs, largely to counter Russia.
The document said: “Our strategy will ensure Russia understands that any use of nuclear weapons, however limited, is unacceptable.”
The US military is concerned that Vladimir Putin views American nuclear weapons as too big to be used – meaning they are no longer an effective deterrent.
Developing smaller nuclear weapons would challenge the Kremlin’s assumption, it has argued.
However, whilst low-yield weapons are less powerful than conventional nuclear weapons, they still have the potential to be incredibly destructive.
The atomic bomb dropped on the Japanese city of Nagasaki at the end of World War Two had a similar level of explosive power, and killed more than 70,000 people.
Dr Gronlund added: “The administration’s new policy also shoots a big hole in the Nuclear Non-Proliferation Treaty, which is key to US security.
“It simply rejects the US obligation to take steps toward nuclear disarmament.
“Since the end of the Cold War, the United States has made progress—albeit slow progress—in reducing the number, types and role of its nuclear weapons. The new policy reverses that progress.
“The NPR is a giant slap in the face of the non-nuclear weapon states, who are already fed up with the slow progress of the United States and Russia.
“President Trump is embarking on a reckless path—one that will reduce US security both now and in the longer term.”