United States and weapons of mass destruction
The United States is known to have possessed three types of weapons of mass destruction: nuclear weapons, chemical weapons, and biological weapons. The U.S. is the only country to have used nuclear weapons in combat, when it detonated two atomic bombs over the Japanese cities of Hiroshima and Nagasaki during World War II. It had secretly developed the earliest form of the atomic weapon during the 1940s under the title "Manhattan Project". The United States pioneered the development of both the nuclear fission and hydrogen bombs (the latter involving nuclear fusion). It was the world's first and only nuclear power for four years (1945–1949), until the Soviet Union managed to produce its own nuclear weapon. The United States has the second largest number of deployed nuclear weapons in the world, after Russia.
Bulletin of the Atomic Scientists
Although the arms race and the Cold War, which were focuses of the "Bulletin" for many of the earlier years, are no longer occurring, the publication still focuses on the nuclear dangers that exist in the world today. As more countries such as Pakistan and India have tested nuclear weapons, the "Bulletin" has focused on the dangers posed by these countries. The "Bulletin's" bi-monthly "Nuclear Notebook" is written by Federation of American Scientists experts Hans Kristensen and Matt Korda and tracks the number of nuclear weapons in the world by country. Robert "Stan" Norris, who was a founding co-author of the Nuclear Notebook, retired from the Notebook in 2018, although he is still a senior fellow at FAS. In 2015, the "Bulletin" added the Nuclear Notebook Interactive, an infographic that illustrates which countries have nuclear weapons and when they got them, and how many nuclear warheads they have in any given year. All nine nuclear-armed states are featured: the United States, Russia, China, India, Pakistan, France, Britain, Israel, and North Korea.