A “Broken Arrow” is defined as an unexpected event involving nuclear weapons that results in the accidental launching, firing, detonating, theft or loss of the weapon.
A nuclear strike by a Soviet foxtrot-class submarine B-59 was averted by Vasily Arkhipov, one of the officers aboard. The submarine had been discovered and targeted by a US aircraft carrier, attempting to force its surfacing. The submarine’s communication had broken off and unsure if the war had started, Captain Savitsky decided to launch the nuclear missile, only Arkhipov refused his mandatory approval, averting a potential WWIII.
Further materials:
https://futureoflife.org/background/nuclear-close-calls-a-timeline/
