Nuclear holocaust
From Memory Alpha, the free Star Trek reference.
Nuclear holocaust is another name for a nuclear war or the state of a planet thereafter.
The Talosians were once a technologically-advanced culture but a nuclear holocaust left Talos IV virtually uninhabitable. (TOS: "The Cage")
Kevin and Rishon Uxbridge were the only survivors of a nuclear holocaust on Delta Rana IV. (TNG: "The Survivors")
Humanity experienced a nuclear holocaust following the Third World War of circa 2026. Six hundred million were killed and major cities were destroyed. This led to the post-atomic horror. (TNG: "Encounter at Farpoint"; Star Trek: First Contact)
