>>/38944/
D5?

DEFENSE SUPPORT OF CIVIL AUTHORITIES1-5.DSCA  addresses  the  consequences  of  man-made  or  natural  disasters  and  incidents  beyond  the  capabilities of civilian authorities. U.S. Army forces do not conduct stability tasks within the United States and its territories; under U.S. law, the Federal Government and state governments are responsible for those tasks.  Instead,  Army  forces  conduct  DSCA,  when  requested,  providing  their  expertise  and  capabilities  to  lead agency authorities.

https://fas.org/irp/doddir/army/atp3-57-60.pdf

any militaryfags around. 
what else maybe in the military could D5 be?

Division 5
Protocol D1-6