Building the bomb, tickling the dragon

Norris Bradbury, group leader for bomb assembly, stands next to the partially assembled Gadget atop the test tower at Los Alamos in 1945.
Norris Bradbury, group leader for bomb assembly, stands next to the partially assembled Gadget atop the test tower at Los Alamos in 1945.
U.S. Gov./Cover Images via Reuters Connect

“Tickling the dragon’s tail.” That’s how the small group of physicists working at Los Alamos in the 1940s under the watch of Robert Oppenheimer described the dangerous job of assembling a nuclear core for the first atomic bomb. One wrong move and a chain nuclear reaction — the dragon — could have wiped them all out.

Even though the Manhattan Project was America’s most sensitive and secretive task — and the focus of the new Christopher Nolan film that opens tomorrow — Canada and the UK also contributed to the work. And at the very heart of it was a Jewish Canadian scientist named Louis Slotin, who emerged as the bomb assembler-in-chief. He worked with the radioactive material to build the core of the bomb — literally tickling the dragon by hand — a skill that led to his fame, but also to his gruesome, slow death by radiation poisoning in 1946.

Slotin was one of about 35 Canadian scientists working at Los Alamos. But Canada’s most crucial contribution — outside the academic work done in places like the famed Montreal Lab – was likely the Eldorado Mine on Great Bear Lake in the Northwest Territories, which supplied uranium to the bomb project. Canada’s uranium was hauled down from the north and refined in a lovely little Lake Ontario town between Ottawa and Toronto called Port Hope, before being shipped to Los Alamos to be used in Fat Man and Little Boy, the bombs that were eventually dropped on Hiroshima and Nagasaki.

The US-Canada link was so strong that by 1944 the first nuclear reactor outside of the United States was built in Canada in a place called Chalk River, not far from Ottawa — which leads to another fascinating thread … In 1952, there was a nuclear meltdown at the Chalk River plant, and a 28-year-old American naval officer with expertise in nuclear power named Jimmy Carter — yes, the man who would go on to become the 39th US president — rushed in and prevented the accident from becoming catastrophic.

Still, as the new film “Oppenheimer” examines, developing the bomb remains a moral morass, one which Oppenheimer and Slotin openly struggled with. Were they, as Oppenheimer later claimed to have said, the destroyers of worlds, or did they save lives? That moral debate continues.

As nuclear fears reemerge with the war in Ukraine and the NATO alliance is reanimated in its purpose, it’s worth examining again how the world should handle its nuclear capabilities. While Oppenheimer’s later life was subsumed by political suspicion that he was a Communist (there is no evidence he gave the Russians any secrets), Slotin never lived to see that. In 1946, while working at Los Alamos, he was tickling the dragon’s tail by hand when there was an accident, and he was fatally irradiated. He cooked from the inside and slowly, painfully, melted down. His life is a stark reminder that the nuclear dragon is still very much alive, and as we covered recently on our GZERO World PBS program when Ian Bremmer interviewed the International Atomic Energy Agency chief Rafael Grossi, the dragon remains very, very difficult to tame.

More from GZERO Media

- YouTube

In this Global Stage panel recorded live in Abu Dhabi, Becky Anderson (CNN) leads a candid discussion on how to close that gap with Brad Smith (Vice Chair & President, Microsoft), Peng Xiao (CEO, G42), Ian Bremmer (President & Founder, Eurasia Group and GZERO Media), and Baroness Joanna Shields (Executive Chair, Responsible AI Future Foundation).

A Palestinian Hamas militant keeps guard as Red Cross personnel head towards an area within the so-called “yellow line” to which Israeli troops withdrew under the ceasefire, as Hamas says it continues to search for the bodies of deceased hostages seized during the October 7, 2023, attack on Israel, in Gaza City, on November 2, 2025.
REUTERS/Dawoud Abu Alkas
Farmers proceed to their fields for cultivation under Nigerian Army escort while departing Dikwa town in Borno State, Nigeria, on August 27, 2025. Despite the threat of insurgent attacks, farmers in Borno are gradually returning to their farmlands under military escort, often spending limited time on cultivation.
REUTERS/Sodiq Adelakun
US President Donald Trump (sixth from left) and Japanese Prime Minister Sanae Takaichi (seventh from left) arrive at the nuclear-powered aircraft carrier USS George Washington (CVN-73) in Yokosuka City, Kanagawa Prefecture, Japan, on October 28, 2025.
Akira Takada / The Yomiuri Shimbun via Reuters Connect

Last Thursday, US President Donald Trump announced that Washington will restart nuclear weapons testing, raising fears that it could end a 33-year moratorium on nuclear-warhead testing.

Behind every scam lies a story — and within every story, a critical lesson. Anatomy of a Scam, takes you inside the world of modern fraud — from investment schemes to impersonation and romance scams. You'll meet the investigators tracking down bad actors and learn about the innovative work being done across the payments ecosystem to protect consumers and businesses alike. Watch the first episode of Mastercard's five-part documentary, 'Anatomy of a Scam,' here.

- YouTube

"We are seeing adversaries act in increasingly sophisticated ways, at a speed and scale often fueled by AI in a way that I haven't seen before.” says Lisa Monaco, President of Global Affairs at Microsoft.

US President Donald Trump has been piling the pressure on Russia and Venezuela in recent weeks. He placed sanctions on Russia’s two largest oil firms and bolstered the country’s military presence around Venezuela – while continuing to bomb ships coming off Venezuela’s shores. But what exactly are Trump’s goals? And can he achieve them? And how are Russia and Venezuela, two of the largest oil producers in the world, responding? GZERO reporters Zac Weisz and Riley Callanan discuss.