Canon

LUX

From Halopedia, the Halo wiki

LUX is a United Nations Space Command flagword to be declared prior to a tactical nuclear deployment.[1]

Usage

As part of the UNSC's ongoing URNA Southwest Campaign during the Battle for Earth in November, 2552, LUX was declared in anticipation of a tactical nuclear deployment against multiple shielded Covenant positions centered around Free-fire Area OZONE in southeastern Arizona. The UEG issued an emergency evacuation broadcast as part of the order.[1]

Trivia

"Lux" is the Latin word for "light."

Sources