Volodymyr Zelensky ‘could build a nuclear bomb in months’

Kyiv could rapidly develop a rudimentary weapon similar to that dropped on Nagasaki in 1945 to stop Russia if the US cuts military aid.

A firefighter working at the site of a Russian strike in Brovary, near Kyiv, on Thursday. Picture: Ukraine Emergency Service via AFP

Ukraine could develop a rudimentary nuclear bomb in less than a year if Donald Trump withdraws US military assistance, according to a briefing paper prepared for the Ukrainian Ministry of Defence.

The country would quickly be able to build a basic device from plutonium with a similar technology to the Fat Man bomb dropped on Nagasaki in 1945, the report states. “Creating a simple atomic bomb, as the US did within the framework of the Manhattan Project, would not be a difficult task 80 years later,” the document says.

With no time to build and run the large facilities required to enrich uranium, wartime Ukraine would have to rely instead on using plutonium extracted from spent fuel rods taken from Ukraine’s nuclear reactors.

Ukraine still controls nine operational reactors and has significant nuclear expertise despite having given up the world’s third-largest nuclear arsenal in 1996.

The report says: “The weight of reactor plutonium available to Ukraine can be estimated at seven tonnes ... A significant nuclear weapons arsenal would require much less material ... the amount of material is sufficient for hundreds of warheads with a tactical yield of several kilotonnes.”

Such a bomb would have about one-tenth the power of Fat Man, the document’s authors conclude.

“That would be enough to destroy an entire Russian air base or concentrated military, industrial or logistics installations. The exact nuclear yield would be unpredictable because it would use different isotopes of plutonium,” said the report’s author, Oleksii Yizhak, head of department at Ukraine’s National Institute for Strategic Studies, a government research centre that acts an advisory body to the presidential office and the National Security and Defence Council of Ukraine.

The plutonium would need to be imploded using “a complicated conventional explosion design, which must occur with a high detonation wave velocity simultaneously around the entire surface of the plutonium sphere”, the report reads. Producing such a complex blast would be challenging but within Ukraine’s expertise, according to the briefing.

Last month President Volodymyr Zelensky said he had told Mr Trump that Ukraine would need nuclear weapons to guarantee his country’s security if it were prevented from joining NATO, as President Vladimir Putin has demanded. Mr Zelensky later said he had meant there was no alternative security guarantee, and Ukrainian officials have since denied Kyiv is considering nuclear rearmament.

The paper, published by military think tank the Centre for Army, Conversion and Disarmament Studies, has been shared with the country’s deputy defence minister and is due to be presented at a conference attended by Ukraine’s ministers for defence and strategic industries.

It is not endorsed by the Kyiv government but sets out the legal basis under which Ukraine could withdraw from the nuclear non-proliferation treaty, the ratification of which was contingent on security guarantees given by the US, UK and Russia in the 1994 Budapest memorandum.

The agreement stated Ukraine would surrender its nuclear arsenal of 1734 strategic warheads in exchange for the promise of protection. “The violation of the memorandum by the nuclear-armed Russian Federation provides formal grounds for withdrawal from the NPT and moral reasons for reconsideration of the non-nuclear choice made in early 1994,” the paper states.

Russian troops are gaining momentum as they advance in the Donbas region and Trump has pledged to cut US military aid unless Kyiv submits to peace talks with Putin. Bryan Lanza, a Trump adviser, has said Ukraine will have to surrender Crimea. This week Donald Trump Jr taunted Mr Zelensky, posting on X: “You’re 38 days from losing your allowance.”

Ukrainian forces are heavily dependent on US weaponry, and any reduction in the flow of Western arms into the country, let alone a complete curtailment, would have catastrophic consequences on the battlefield.

That has prompted Ukrainians to look for a way to take matters into their own hands. “We face an existential challenge. If the Russians take Ukraine, millions of Ukrainians will be killed under occupation,” said Valentyn Badrak, director of the centre that produced the paper. “There are millions of us who would rather face death than go to the gulags.”

Western experts believe it would take Ukraine at least five years to develop a nuclear weapon and a suitable carrier, but Badrak insists Ukraine is less than a year from building its own ballistic missiles. “In six months Ukraine will be able to show that it has a long-range ballistic missile capability: we will have missiles with a range of 1000km,” Badrak said.

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