Satellite images have revealed significant new construction at Iran's Natanz and Isfahan nuclear sites, which were heavily damaged by United States and Israeli strikes last year. The photos show roofs being built over the rubble of key facilities, as well as increased excavation and dirt piles that experts believe are linked to the creation of a new underground bunker. Analysts say these coverings are likely intended to conceal recovery efforts and any remaining nuclear materials from satellite surveillance, rather than to rebuild the sites for immediate use. Iran has not allowed international inspectors to visit the damaged locations since the attacks, and the activity comes amid renewed threats and demands from the United States for Iran to negotiate over its nuclear program. The construction marks the first major visible activity at these sites since last summer's conflict, raising new questions about Iran's nuclear ambitions and the effectiveness of the strikes.