Jennifer Cole at the Royal United Services Institute (RUSI) explains, nuclear war is no longer on the UK’s “National Risk Register” – although the likelihood of a nuclear bomb being detonated by a terrorist group is thought to be “low but not negligible. A nuclear strike isn’t a reasonable worst-case scenario anymore,” she says. Her colleague at RUSI, Tom Plant, also notes that Britain’s Trident submarines – armed with nuclear warheads – are currently at a readiness state of several days’ “notice to fire”. At the height of the Cold War, missiles could have been launched in 15 minutes. “We’re not in the prevailing circumstances of the Cold War where we are in a perceived high level of threat,” he says.