The initial DEFCON system had "Alpha" and "Bravo" conditions (under DEFCON 3) and Charlie/Delta under DEFCON 4, plus an "Emergency" level higher than DEFCON 1 with two conditions: "Defense Emergency" and the highest, "Air Defense Emergency" ("Hot Box" and "Big Noise" for exercises).
Sistem DEFCON awalnya memiliki kondisi "Alpha" dan "Bravo" (di bawah DEFCON3) dan Charlie/Delta di bawah DEFCON4, plus tingkatan "Emergency" yang lebih tinggi daripada DEFCON1 dengan dua kondisi: "Defense Emergency" dan "Air Defence Emergency" (paling tinggi).