In January, the Bulletin of the Atomic Scientists reset the famous Doomsday Clock at 90 seconds to midnight, the closest to Armageddon the world has ever been, according to the expert nonprofit. The clock’s second hand must have moved a bit closer in the months since, with Russian President Vladimir Putin responding to the world’s opposition to his 2022 invasion of Ukraine by suspending the New START Treaty to limit nuclear warheads and announcing plans to station Russian nuclear-tipped missiles in Belarus.

On Wednesday, an eminent group of arms control experts including a University of Maryland physicist that gathered at the Edward St. John Learning and Teaching Center on campus had few comforting words for the audience.

“I think all of us who have devoted our lives to arms control or who have spent significant amounts of time in this area will tell you that probably most of us haven’t had a good night’s sleep in more than a year,” said Susan Eisenhower, an author and international security expert (and granddaughter of U.S. President Dwight D. Eisenhower) who moderated the panel. The discussion followed introductions by William “Brit” Kirwan, a former UMD president and chancellor emeritus of the University System of Maryland and Nancy Gallagher, a research professor in the School of Public Policy and director of the Center for International and Security Studies at Maryland.

Noting that the panel was composed entirely of physicists, UMD Distinguished University Professor Emeritus Roald Sagdeev said it was fitting that members of the field that created nuclear weapons lead the fight to prevent their use.

“We let the genie out of the bottle,” said Sagdeev, former head of the Soviet space agency IKI and an adviser to former Russian President Mikhail Gorbachev.

In his assessment of risks, he said he saw little chance that Putin would employ small, tactical nuclear weapons against Ukraine, which might have little effect on the war’s progress but cost him any support from countries like China and India. But what about the prospect of an embattled and faltering Putin launching an apocalyptic strike if his regime were threatened? “Imagine Hitler, sitting in his bunker, had had a nuclear keyboard,” Sagdeev said. “Would he have pressed it at the very end? That’s where we are.”

Physicist Richard Garwin, for decades one of the United States’ most prominent scientists and author of the design of the first hydrogen bomb in 1952, said Putin’s disregard of prior agreements and lack of respect for the rule of law are dialing up the danger, and threatening to set a new precedent for the use of nuclear weapons. But the U.S. should not respond by beginning new nuclear tests and reviving the arms race, he said.

Frank von Hippel, a former national security staffer in the White House Office of Science and Technology Policy (OSTP) and now a senior research physicist and professor emeritus with Princeton University’s Program on Science and Global Security, addressed the widely accepted concept of the unwinnability of a nuclear war—a concept important to deterrence strategy. But von Hippel took it further: “I’m going to argue nuclear deterrence is obsolete.” Modern conventional weapons can accomplish military objectives, while nuclear arms are expensive tools of mass slaughter with little strategic value. The world should abolish them, he said.

“I hope in the not-too-distant future we can once again partner with our Russian and Chinese colleagues in this effort, as we did with Sagdeev and his colleagues” during arms control talks with the USSR, von Hippel said.

The lack of contact between the U.S. and Russia since the onset of the war in Ukraine puts the world at risk from a split-second miscalculation, said John Holdren, former OSTP director, senior adviser to former President Barack Obama and now a research professor in Harvard University’s Kennedy School of Government and co-director of the Science, Technology, and Public Policy Program in the Belfer Center for Science and International Affairs.

“It is crazy not to be talking, absolutely crazy,” Holdren said. “In the worst times of the Cold War, we still managed to talk.”

Holdren called for the U.S. to embrace several measures including: a “no first use” policy on nuclear weapons, “de-alerting” so they can’t be thrown into use quickly and providing more time to avoid errors, scrapping silo-based intercontinental ballistic missiles, and aggressively pursuing agreements to drastically cut warhead inventories by 80% or more—and reducing further from that starting point.

Among Sagdeev’s recommendations was working to make existing nuclear weapons safer and less likely to be used in error. For his part, von Hippel’s modest proposal was to lock leaders of nuclear armed powers overnight in Hiroshima’s Peace Memorial Museum to ponder the world’s peril.