Only after construction on the site began that year did it finally become clear that two secretive agencies were behind a project that experts say will be the subcontinent’s largest military-run complex of nuclear centrifuges, atomic research laboratories and weapons and aircraft testing facilities. Among the project‘s aims: to expand the government’s nuclear research, to produce fuel for India’s nuclear reactors, and to help power the country’s fleet of new submarines, one of which underwent sea trials in 2014.