Defcon four, also called “Defcon level 4” or “Double Take” is an increase in intel gathering and strengthening of security protocols. Defcon four (4) readiness is considered “Above Normal Readiness”.
This is just one level lower than “Normal readiness” with the military on green alert status. Defcon four (4) was the current alert status of the United States military until it was changed to three recently. 4 is a common status to be at.