Related questions on Metaculus:

• If a nuclear detonation occurs by 2050, will the first detonation be launched accidentally or without authorization?

• Will there be at least 1 fatality due to accidental or unauthorised nuclear detonation by 2024?

• Will there be at least one fatality due to inadvertent nuclear detonation by 2024?

• Will there be at least one fatality due to deliberate nuclear detonation by 2024?

Barrett et al. (2013) distinguish between accidental/unauthorised, inadvertent, and deliberate nuclear launches or detonations:

"In an accidental or unauthorized launch or detonation, system safeguards or procedures to maintain control over nuclear weapons fail in such a way that a nuclear weapon or missile launches or explodes without direction from leaders."

"In an inadvertent detonation, the attacking nation mistakenly concludes that it is under nuclear attack and launches one or more nuclear weapons in what it believes is a counterattack."

"In a deliberate detonation, the attacking nation decides to launch one or more nuclear weapons either in response to a genuine nuclear attack or without believing that it is under nuclear attack."

The only non-test nuclear detonations as of 2021 were deliberate detonations on Japan in 1945. However there have been several opportunities where inadvertent and deliberate launches had nearly occurred. Inadvertent launches could also occur if weapons facilities fall out of maintenance, if subordinates disobey the chain of command, or if non-state actors infiltrate a nuclear weapons facility (similar to the 2012 Plowshares protest). Understanding which type of detonation are most likely to precipitate a conflict may help us understand which kinds of risks are most urgent, as well as which kinds of conflicts might develop.