The Bikini code is specifically used to classify terrorist threats - other military threats will have different code names. The alert state is indicated by one of a number of colours, depending on how serious, specific and imminent the threat is:
Bikini White is the lowest level. There is no known threat.
Bikini Black means that there is a possibility of a terrorist attack, but it could occur anywhere at any time.
Bikini Amber states that there is a known threat to an unknown Government target within a specific period of time.
Bikini Red means that a known threat to a specific target is imminent.
The definition of the term Code Red is as follows:
Indicates emergency situation: used to indicate that a difficult or dangerous situation has deteriorated drastically so as to constitute an emergency.
The term is often used by military and government in connection with terrorist threats and global health situations.
The colour red is often associated with emergencies and danger as well as energy. Death is also commonly associated with this colour through its connection with blood.