Two secretive agencies are behind a nuclear city 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 when it’s completed, probably sometime in 2017, says a report published by the Foreign Policy. According to the report, the project is meant 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. But another, more controversial ambition, according to retired Indian government officials and independent experts in London and Washington, is to give India an extra stockpile of enriched uranium fuel that could be used in new hydrogen bombs, also known as thermonuclear weapons, substantially increasing the explosive force of those in its existing nuclear arsenal. India’s close neighbors, China and Pakistan, would see this move as a provocation: Experts say they might respond by ratcheting up their own nuclear firepower. New Delhi has never published a detailed account of its nuclear arsenal, which it first developed in 1974, and there has been little public notice outside India about the construction at Challakere and its strategic implications. But a lengthy investigation by the Center for Public Integrity (CPI), including interviews with local residents, senior and retired Indian scientists and military officers connected to the nuclear program, and foreign experts and intelligence analysts, has pierced some of the secrecy surrounding the new facility, parts of which are slated to open in 2016. This new facility will give India a nuclear capability — the ability to make many large-yield nuclear arms — that most experts say it presently lacks. The independent Stockholm International Peace Research Institute (SIPRI) estimates that India already possesses between 90 and 110 nuclear weapons, as compared to Pakistan’s estimated stockpile of up to 120. China, which borders India to the north, has approximately 260 warheads. The enlargement of India’s thermonuclear program would position the country alongside the United Kingdom, the United States, Russia, Israel, France, and China, which already have significant stockpiles of such weapons. Spokesmen for the two organizations involved in the Challakere construction, the Defense Research and Development Organisation (DRDO) and the Bhabha Atomic Research Centre (BARC), which has played a leading role in nuclear weapons design, declined to answer any of CPI’s questions, including about the government’s ambitions for the new park. The Indian Ministry of External Affairs also declined to comment. Western analysts, speaking on condition of anonymity, say, however, that preparation for this enrichment effort had been underway for four years, at a second top-secret site known as the Rare Materials Plant, 160 miles to the south of Challakere, near the city of Mysore. Satellite photos of that facility from 2014 have revealed the existence of a new nuclear enrichment complex that is already feeding India’s weapons program and, some Western analysts maintain, laying the groundwork for a more ambitious hydrogen bomb project. Gary Samore, who served from 2009 to 2013 as the White House coordinator for arms control and weapons of mass destruction, said there was little misunderstanding. “I believe that India intends to build thermonuclear weapons as part of its strategic deterrent against China,” said Samore. It is unclear, he continued, when India will realize this goal of a larger and more powerful arsenal, but “they will.” A former senior British official who worked on nuclear issues likewise said intelligence analysts on both sides of the Atlantic are “increasingly concerned” about India’s pursuit of thermonuclear weapons and are “actively monitoring” both sites. US officials in Washington said they shared this assessment. “Mysore is being constantly monitored, and we are constantly monitoring progress in Challakere,” a former White House official said.