At their core, nuclear weapons are devices designed to release an enormous amount of energy through nuclear reactions, either by splitting atoms (fission) or combining them (fusion). Nine countries hold the 13,000 nuclear weapons in the global stockpile. That's less than during the Cold War but it doesn't change the fact that these bombs are still a threat to global humanity. So how do they work and are we close to nuclear war? President Trump’s threat on Wednesday to restart the testing of nuclear weapons has raised numerous knotty questions about national and global security. The United States spends tens of billions ... All existing nuclear weapons derive some of their explosive energy from nuclear fission reactions. Weapons whose explosive output is exclusively from fission reactions are commonly referred to as atomic bombs or atom bombs (abbreviated as A-bombs).
