Def. Con. One

One" is a single by Pop Will Eat Itself released in July 1988 from the album This Is the Day...This Is the Hour...This Is This!.

It is an early example of a song composed by sampling other songs and musical scores, including "I Wanna Be Your Dog" by the Stooges, "Funkytown" by disco band Lipps Inc., the 1973 hit "Crazy Horses" by the Osmonds and The Twilight Zone theme tune.

The title comes from the United States' Defense Readiness Condition DEFCON 1, which signifies that "war is imminent."

The live tracks that appear on the 12" and CD editions were recorded in Gothenburg, Sweden during a tour in March 1988.

It features the band performing the song in front of a large image of the This Is the Day...This Is the Hour...This Is This!