Short answers, pulled from the story.
Nuclear weapons were first and only used in combat during August 1945, when the United States dropped atomic bombs on Hiroshima on August 6 and on Nagasaki on August 9. The two bombings killed between 150,000 and 246,000 people and contributed to Japan's surrender on the 15th of August 1945.
According to figures cited by the former chair of the United Nations disarmament committee, there are more than 16,000 strategic and tactical nuclear weapons ready for deployment and another 14,000 in storage. The U.S. holds nearly 7,000 ready for use and 3,000 in storage; Russia holds about 8,500 ready for use and 11,000 in storage. In early 2019, more than 90 percent of the world's 13,865 nuclear weapons were owned by Russia and the United States.
The Doomsday Clock is maintained by the Bulletin of the Atomic Scientists since 1947 to visualize how close the world is to nuclear war. Since 2026, the Clock has been set at 85 seconds to midnight, the closest it has ever been. Its previous high points were two minutes to midnight in 1953, after the U.S. and Soviet Union began testing hydrogen bombs, and again in 2018.
The 1962 Cuban Missile Crisis is most often cited as the closest call, with the Soviet Union placing medium-range ballistic missiles 90 miles from the United States. On the 26th of September 1983, Soviet officer Stanislav Petrov correctly identified a false alarm of an American first strike, potentially averting retaliation. In November 1983, the Soviet Union raised nuclear readiness after mistaking the NATO exercise Able Archer 83 for cover to launch a real first strike.
A peer-reviewed study published in Nature Food in August 2022 estimated that a full-scale nuclear war between the U.S. and Russia would kill 360 million people directly, with a further 5 billion people dying from starvation. A smaller conflict between India and Pakistan would kill more than 2 billion people.
South Africa is the only country to have manufactured a complete nuclear arsenal and then voluntarily dismantled it. South Africa developed nuclear weapons during the 1970s and early 1980s, and during the 1990s it destroyed its domestically produced nuclear weapons and abandoned further production.