Environmental group Greenpeace has warned that the failing inner containment shell — the so-called "sarcophagus" hastily built around Chornobyl's destroyed reactor No. 4 after the 1986 disaster — risks an uncontrolled collapse that could release radioactive material into the environment. The outer steel arch installed in 2016 to enclose the sarcophagus was pierced by a Russian drone in February 2025 and, despite repair efforts, its containment function has not been fully restored, leaving an estimated four tonnes of highly radioactive dust and fuel particles vulnerable to dispersal. The plant's director has described the situation as "very dangerous," warning that even a missile strike within 200 metres could produce a seismic-like shock, while Greenpeace notes that ongoing Russian military activity over the site — which carries an estimated €500 million repair bill — makes the necessary stabilisation work extremely difficult to carry out.