Drone strikes near the shattered reactor at Chornobyl Nuclear Power Plant in Ukraine are putting the safety of millions of people at risk, a top United Nations official warned Thursday, in one of the starkest cautions yet about the war's proximity to a site still associated with the deadliest nuclear accident in history.

Alexander De Croo, Administrator of the UN Development Programme (UNDP), told reporters via video link from Kyiv that a drone strike on the plant's protective structure, the massive steel arch built to contain radioactive material from the 1986 disaster, could have had catastrophic consequences. "This is gambling with the safety of millions of people," De Croo said.

The warning underscores a growing fear among international officials: that nearly four years of grinding war between Russia and Ukraine has repeatedly brought armed conflict into contact with critical nuclear infrastructure, raising the specter of a radiological disaster layered on top of a humanitarian one.

A Site Still Marked by Catastrophe

Chornobyl, located a few miles north of the Ukrainian capital, was the site of the 1986 explosion that remains the worst nuclear accident in history. A reactor exploded and burned, killing 35 people directly and releasing a radioactive cloud that drifted across much of Europe. In the years following the disaster, hundreds of cases of thyroid cancer emerged in communities near the plant, and radioactive contamination lingered in unexpected places. Hundreds of square miles of sheep pasture in Wales, Cumbria and Scotland remained under restrictions, with hundreds of thousands of animals requiring testing for radioactivity before they could enter the food supply.

The protective structure now at risk, a massive arch-shaped shelter, was engineered specifically to contain the remaining radioactive material at the destroyed reactor and prevent further leakage into the surrounding environment. Even decades after the original accident, concerns persisted about radioactive elements slowly leaching into groundwater near the plant and toward Kyiv's drinking supply from pits where the most dangerous debris had been buried. Any breach of the containment structure could reactivate concerns that had only partially eased in the decades since the disaster.

Nuclear Sites Caught in the Crossfire

The war in Ukraine has repeatedly placed nuclear facilities in the path of military activity. Ukraine's power plants, including its active reactors, have faced shelling, occupation and disruptions to external power supplies necessary to keep cooling systems running safely. This echoes warnings from nuclear safety experts that armed conflict near reactors poses risks unlike almost any other form of infrastructure damage.

Nuclear accidents historically have stemmed from a combination of design flaws, natural disaster and human error, as seen in the 1979 partial meltdown at Three Mile Island in the United States and the 2011 meltdown at Fukushima in Japan, where a tsunami disabled emergency generators and led to widespread contamination. In both cases, public trust was damaged further when it emerged that authorities had downplayed or concealed known risks. War introduces a new and less predictable variable: the possibility that a strike, whether deliberate or accidental, could compromise containment structures or cooling systems built to prevent radioactive release.

"This is gambling with the safety of millions of people," De Croo said, describing the risk posed by drone strikes near the site's protective structure.

Why It Matters Beyond Ukraine's Borders

Radioactive contamination does not respect national boundaries. The 1986 Chornobyl disaster demonstrated that a nuclear accident in one country can spread fallout across an entire continent within days. A new incident at the same site, even a partial breach of the protective structure, could carry similar transnational consequences, affecting air, water and soil far beyond Ukraine.

De Croo's remarks add to mounting concern from international bodies that the war's expansion into the vicinity of nuclear sites represents an escalation with consequences that could far outlast the conflict itself. Unlike conventional battlefield damage, radioactive contamination can persist for decades, rendering land unusable and posing long-term health risks, including elevated cancer rates, to populations living near affected areas.

As the war continues, UN officials and nuclear safety monitors are likely to intensify calls for protected zones around nuclear facilities and for both sides to avoid military activity near sites like Chornobyl, where the margin for error remains perilously thin.