The default response to US policy, some post-Cold War nuclear architects say, is discipline and restraint. That could speed up sanctions and isolate Russian President Vladimir Putin, said Rose Gottemoeller, NATO’s deputy secretary general from 2016 to 2019. But no one can rely on calm minds to prevail in such a moment, and real life rarely goes according to plan. World leaders would be angry, offended, scared. Bad communication and confusion could be pervasive. Hackers could add to the chaos. The demands would be great for harsh retaliation – the kind that can be done with nuclear missiles capable of moving faster than the speed of sound. When military and political officials and experts have played Russian-US nuclear tensions in the past, table drills sometimes end with nuclear missiles being fired at continents and oceans, hitting the capitals of Europe and the north. , said Olga Oliker, Program Director for Europe and Central Asia at the International Crisis Group. “And, you know, soon, you just had a global thermonuclear war,” Oliker said. It is a scenario that officials hope to avoid, even if Russia targets Ukraine with a nuclear bomb. Gottemoeller, the US nuclear chief negotiator with Russia for the Obama administration, said the outlines given by President Joe Biden about his nuclear policy so far stick to those of previous administrations in the use of atomic weapons only in “extreme circumstances “. “And just a single Russian demonstration strike, or – horrible as it was – a nuclear use in Ukraine, I do not think it would go to that level,” demanded a nuclear response from the United States, said Gottemoeller, now a lecturer at Stanford University. For former Sen. Sam Nunn, a Georgia Democrat who for nearly a quarter of a century in Congress helped shape global nuclear policy, the choice of Western nuclear use must remain on the table. “This is the doctrine of mutual assured destruction for a very, very long time,” said Nun, now a strategic consultant at the Nuclear Threat Initiative, which he co-founded. “If President Putin used nuclear weapons, or any other country used nuclear weapons first, not in response to a nuclear attack, not in response to an existential threat to their country, this leader should assume that he is putting the world at risk. “There is a high risk of nuclear war and nuclear exchanges,” Nunn said. For US officials and world leaders, discussions about how to respond to a limited nuclear attack are no longer theoretical. In the early hours and days of the Russian invasion, Putin referred to Russia’s nuclear arsenal. He warned Western countries to stay out of the conflict, saying it was putting its nuclear forces on high alert. “Any country that intervened in the Russian invasion would face consequences” like you have never seen in your entire history, “Putin said. How to respond to any use of chemical, biological or nuclear weapons by Russia was among the topics discussed by Biden and other Western leaders when they met in Europe in late March. Three NATO members – the United States, Britain and France – have nuclear weapons. A key concern is that by using some nuclear weapons as regular weapons to be used in battle, Russia could break the nearly eight-decade-old global taboo against using nuclear weapons against another country. Even relatively small tactical nuclear weapons are approaching the power of the atomic bomb dropped by the United States on Hiroshima, Japan, during World War II. Gottemoeller and Nunn praise Biden’s restraint in the face of Putin’s tacit nuclear warnings at the start of the war. Biden made no known move to raise the US nuclear alert regime. The U.S. also postponed a routine test launch of Minuteman III last month to avoid escalating tensions. However, in the short and long term, the world appears to be at greater risk of a nuclear conflict as a result of Putin’s invasion and nuclear threat, according to experts and negotiators in arms control. The weaknesses revealed by Russia’s invasion of its conventional military forces may make Putin feel even more compelled in the future to threaten to use nuclear weapons as his best weapon against the much more powerful United States and NATO. While Gottemoeller argued that the delivery of its Soviet nuclear arsenal from Ukraine in 1994 opened the door to three decades of international integration and development, she said some governments could learn a different lesson from Russia’s nuclear invasion of non-nuclear Ukraine – that need nuclear bombs as a matter of survival. Jeffrey Lewis, a weapons control specialist and professor at the Middlebury Institute, said the nuclear risk was increasing. “And we can say which paths would make this risk increase further. “And certainly a direct confrontation with Russia by forces based in NATO countries is a path to a nuclear war,” Lewis said. Gottemoeller was heartbroken when Putin publicly complained late last month about the “culture of cancellation.” That suggests he was vulnerable to global condemnation of his invasion of Ukraine, and even worse if he broke the taboo on a post-World War II nuclear attack, he said. It would not make sense for a nuclear bomb to explode in a country where Putin sought sovereignty, one next to his own, Nun said. But he said neither did Putin’s announcement of a heightened nuclear alert. As a young aide to Congress during the Cuban Missile Crisis, Nunn saw US officers and pilots in Europe stand by to order nuclear weapons in the Soviet Union. The danger today is not as great as in the Cuban Missile Crisis of 1962, when Soviet nuclear missile development in Cuba increased the risk of a nuclear war with the United States, he said. But the risk of deliberate nuclear escalation is now high enough to make a ceasefire in Ukraine critical, Nun said. The modern threat of cyber-attacks increases the risk of mistaken launch. And it is not clear how vulnerable US and especially Russian systems are to such hacking attempts, he said. “Putin was very reckless when he fired his nuclear weapons,” Nun said. “And I think that has made everything more dangerous, including a blunder.”