The administration of President Donald Trump on Friday reversed long-standing United States policy on the use of nuclear weapons, taking a far more aggressive stance over their possible use. In particular, the revised policy makes it clear that Russia would face dire consequences should it contemplate the use of any similar weapons, and sends a clear message to Moscow that any future interventions in eastern Europe will need to be carefully thought out.

The policy too acknowledges that China is a potential adversary, but when it comes to North Korea, the administration makes it clear that any nuclear launch from Pyongyang will result in the full destruction of that nation. What is most troubling is that the policy comes at a time when Washington and Pyongyang have engaged in a war of words, with President Trump guilty of shooting from the lip.

This aggressive change in policy is worrisome in that the trend since the end of the Cold War has been to move away from dependence on a nuclear arsenal, reducing the number of warheads, and building a defence policy on conventional forces. At a time now when the real threat comes from terrorist organisations, the move to harden a nuclear policy seems a little unwise.

While the Trump administration’s new policy does not increase the number of nuclear weapons, it nevertheless represents a dangerous escalation by loosening the rules over the use of battlefield or tactical use — and once that genie is out of the bottle, there is no going back.

Recent incidents show that the threat of a nation determined to use cyber capabilities in an aggressive manner is a reality, and the revision of the nuclear policy now sends a message that Washington’s priorities are elsewhere.

US presidents from George Bush senior down to Barack Obama, have each taken steps to ensure that the prospect of atomic warfare and the use of nuclear weapons has been reduced and removed as a focus of Pentagon thinking. President Obama in particular took realistic measures to curtail nuclear dependence. As with many aspects of Obama-era measures, this White House administration is intent on ripping up his legacies. In doing so now, the White House is taking an overtly aggressive posture, and the timing of the change will not go unnoticed in Moscow, Beijing or Pyongyang.

We can never allow nuclear weapons to be unleashed again. That key principle now has been bruised by this new policy.