The risk of a nuclear war breaking out is at the highest level since the end of the Cold War, a United Nations report has said amid rising tension between two major nuclear powers -- the U.S. and North Korea.

A study by the UN Institute for Disarmament Research (UNIDIR) stressed that the world is now facing "full of potential for catastrophe" with more than 15,000 nuclear weapons possessed by nine states.

"The threat of a nuclear weapon detonation event in 2017 is arguably at its highest in the 26 years since the collapse of the Soviet Union," the research said.

It warns that interconnected sensors, networks and the possibilty of 'nuclear-enabled' drones could mean that one error could quickly escalate, causing misunderstandings and even 'accidental wars'.

The use of automated systems also leads to 'misplaced confidence' which could reveal 'new points of vulnerability', making it more likely to fall into the wrong hands, ie. terrorists.

"The return of Cold War-like confrontational postures has hindered international cooperation and confidence-building," it added. "Nuclear deterrence works – up until the time it will prove not to work… the risk is inherent and, when luck runs out, the results will be catastrophic," the report concluded.

The U.S. is currently working together with its allies to respond to North Korea's latest missile tests and a possible sixth nuclear weapons test -- which Washington sees as a threat to global stability.

The Trump administration is hoping that China will help rein in North Korea in exchange for other considerations. Last week, Trump said he would not declare China a currency manipulator, pulling back from a campaign promise, as he looked for help from Beijing, which is the North's dominant trade partner.