The risk of a nuclear weapon being launched by accident is at the highest level since the Cuban missile crisis, a former member of Barack Obama's staff has warned.

Ernest Moniz, who served as US Energy Secretary during Obama's tenure at the White House, said the odds of a catastrophic mistake that would result in a nuclear weapon being launched by miscalculation were shortening.

During the Cold War, the US and the Soviet Union came close to firing nuclear weapons several times after mistakenly thinking they were under attack. The risk of a nuclear arsenal being deployed "is higher than it's been since the Cuban missile crisis", Moniz told the Guardian.

Moniz cited a lack of communication between major nuclear weapons powers and the introduction of new, smaller weapons among the major factors behind the increased risk.

Last month, panic spread through Hawaii after a warning went out that the US island state was the target of a ballistic missile.

The emergency alert, sent to the phones of locals and tourists, carried the message, "Ballistic missile threat inbound to Hawaii. Seek immediate shelter. This is not a drill."

It emerged that it was a false alarm. A retraction message was sent 38 minutes after the original warning.

"Thirty-eight minutes is substantially longer than the decision time that President Trump, President Putin or other leaders with nuclear weapon states would have for a response to a warning about significant incoming missiles," Moniz added.

"We know we've had those warnings many times in history and we've managed so far to dodge the bullet. But dodging the bullets is more difficult when there's not significant communications going on and a lot of tensions between the countries."

Ernest Moniz
Moniz warned the risk of nuclear weapons being launched by mistake was growing. Reuters

The former US Energy Secretary added the risk had been further heightened by the nuclear posture review, which Donald Trump's administration published earlier this month.

Two elements in particular, the development of a low-yield submarine-launched missile and plans to invest $10bn on modernising the B61 gravity bomb, were highly concerning, Moniz explained.

"The use of a new class of submarine-launched smaller weapons seems to us to just add to the issues of miscalculation," he said.

Additionally, the ever-increasing risk of large scale cyberattacks could trigger a nuclear war between two superpowers.

"A major infrastructure cyberattack could not be a nationally endorsed attack at all," said Moniz. "It could be from some third-party hackers who might enjoy a nuclear exchange between the two major powers."