The International Atomic Energy Agency (IAEA) has reported that a drone attack earlier this year has compromised the protective barrier surrounding the Chernobyl nuclear disaster site in Ukraine, rendering it ineffective in containing radioactive materials.

The New Safe Confinement (NSC) structure at Chernobyl was “severely damaged” during the February incident, the IAEA noted, significantly reducing its ability to perform its key safety roles, including the containment of hazardous substances.

Ukraine has blamed Russia for the February 14 drone strike on Chernobyl, an accusation that Moscow has refuted.

According to the IAEA, the attack targeted the NSC, igniting a fire and causing damage to its protective outer layer.

The nuclear agency has advised a substantial overhaul of the extensive steel enclosure, which was initially installed a few years back to facilitate clean-up efforts and bolster safety measures at the site, nearly forty years after the catastrophic nuclear plant incident.

“Limited temporary repairs have been carried out on the roof, but timely and comprehensive restoration remains essential to prevent further degradation and ensure long-term nuclear safety,” IAEA Director General Rafael Mariano Grossi said.

Grossi added that there had been no permanent damage to the NSC’s load-bearing structures or monitoring systems.

The IAEA, which has a permanent presence at the site, will “continue to do everything it can to support efforts to fully restore nuclear safety and security,” Grossi said.

It’s not the first time that Chernobyl has been in the spotlight over the course of Russia’s near four-year war in Ukraine.

Russian forces seized the nuclear plant and its surrounding area in the early days of Moscow’s full-scale invasion, overrunning the plant in February 2022 and holding staff hostage. They left the plant and handed back control to Ukrainian personnel just over a month later.

The NSC is a massive, arch-shaped steel structure built at the Chernobyl site to cover the ruined Number 4 reactor and contain its radioactive material.

As the world’s largest movable land structure, the colossal hangar is a monumental feat of engineering. Built in 2010 and completed in 2019, it was designed to last 100 years and has played a crucial role in securing the site.

The project cost €2.1 billion ($3.68 billion) and was funded by contributions from more than 45 donor countries and organisations through the Chernobyl Shelter Fund, according to the European Bank for Reconstruction and Development, which in 2019 hailed the venture as “the largest international collaboration ever in the field of nuclear safety.”

In April 26, 1986 an explosion tore through the Number 4 reactor at Chernobyl, in what was then the Soviet Union, spreading radioactivity across swathes of Ukraine, Belarus, Russia and beyond.