Methodology

To determine the status of the world’s nuclear powers, 24/7 Wall St. reviewed warhead inventories for each nuclear country as estimated by researchers at the Federation of American Scientists, an organization that works to reduce the spread of nuclear weapons and increase government transparency. FAS researchers used unclassified information to arrive at their estimates. In addition, researchers used a variety of sources, including satellite images, public statements from public officials, newspapers articles, private conversations with government officials, as well as historical analyses over many years were used to ascertain these estimates. 

The year of each country’s first nuclear test, number of deployed warheads, stored warheads, and total inventory, as well as each nation’s military expenditure came from The Stockholm International Peace Research Institute.