New Delhi: In its latest threat against Iran, the United States has used language that strongly implies the possible use of nuclear weapons: “A whole civilisation will die tonight, never to be brought back again,” President Donald Trump said on social media.Since the only weapons capable of extinguishing an entire civilisation are weapons of mass destruction and the only WMDs the US officially possesses are nuclear weapons, there can be no doubt whatsoever about the nature of the threat Trump has delivered.The US is the only country to have actually used nuclear weapons – against Japan in 1945 – and its military is comfortable with the notion of unleashing atomic destruction as a means of ensuring the capitulation of an adversary without the deployment of soldiers in a potentially costly (and perhaps even futile) ground invasion.When US Vice President J.D. Vance echoed Trump’s threat and spoke of the US using military options that it had not considered using yet, a jittery White House social media account rushed to scold critics who said Vance “implies Trump might use nuclear weapons”.Interestingly, the White House Rapid Response account was careful to limit itself to the parsing of Vance’s words and provided no assurance that the US would not be striking Iran with nuclear weapons.This is hardly surprising. As a matter of declared military policy, the US has always reserved the right to use nuclear weapons against an adversary at a time and place of its choosing. The only ‘concession’ the US has made in the nuclear warfighting realm is to not use nuclear weapons against non-nuclear weapon states which are party to the Nuclear Non-Proliferation Treaty (NPT) and in compliance with their obligations under the NPT.This ‘negative security assurance’ (NSA) was first provided by the US in 1978, formally repeated in 1995 when the NPT was indefinitely extended and eventually incorporated into its Nuclear Posture Review. The US NSA was reiterated most recently in 2024 at the Conference on Disarmament.Does this negative security assurance cover Iran? Iran is a non-nuclear weapon state that is a member of the NPT. However, the entire burden of Washington’s policy towards Iran in recent years has been its claim that Iran has violated its obligations under the NPT. Thus, the United States’s official nuclear posture absolutely does not exclude the use of WMDs against Iran.Indeed, in June 2025 the US and its allies pushed through a resolution at the Board of Governors of the International Atomic Energy Agency officially declaring Iran to be not in compliance with its obligations as a non-nuclear weapon state.The tendentious and completely unwarranted June 2025 vote – 19 for to three against with 11 abstentions – was immediately used as a pretext by Israel (and later the US) to attack Iran’s internationally safeguarded civilian nuclear installations. At the time, Trump declared the bombing of Natanz, Fordow and other sites a resounding success.Today, again, the US is insisting its aggression against Iran is aimed at preventing the Islamic Republic from acquiring nuclear weapons. How ironic, then, that its president should threaten a nuclear holocaust against an ancient civilisation and do so while allied with the one country in West Asia that actually possesses nuclear weapons, Israel.