Continuity of government

Continuity of government (COG) is the principle of establishing defined procedures that allow a government to continue its essential operations in case of nuclear war or other catastrophic event.

COG was developed by the British government before and during World War II to counter threats, such as that of the Luftwaffe bombing during the Battle of Britain. The need for continuity-of-government plans gained new urgency with nuclear proliferation.

Countries during the Cold War and afterwards developed such plans to avoid (or minimize) confusion and disorder due to a power vacuum in the aftermath of a nuclear attack.

In the US at least, COG is no longer limited to nuclear emergencies; the Continuity of Operations Plan was activated following the September 11 attacks.

Canada built numerous nuclear bunkers across the country, nicknamed "Diefenbunkers" in a play on the last name of then-Prime Minister John Diefenbaker.

The People's Republic of China (PRC) once operated Underground Project 131, intended to be the PLA headquarters in Hubei during a nuclear conflict. Built due to the Sino-Soviet split during that portion of the Cold War, in 1981, the Project 131 site was turned over to the civilian authorities of the prefecture-level city of Xianning, where it is located.

...
Wikipedia