Not sure? However, in searching this defcon situation, seems our Army went DEFCON 2, last week!
http://macedoniaonline.eu/content/view/6893/2/
If I understand correctly, the JCS has statutory authority to move certain command divisions (ie, CENTCOM, SAC, etc) up and down in DEFCON levels independent of the rest of the military as a whole, without the authorization of the Commander in Chief. This is often to prepare for certain operational maneuvers (ie, during the Cuban Missile Crisis, the military never went beyond DEFCON 3 as a whole, but SAC was upgraded to DEFCON 2 to activate certain training and surveillance missions without the approval of the President)...
In theory, only congress can declare war, and the president is commander in chief with command of the armed forces.. in reality, the military has a lot of latitude to act independently of civilian command.
but if the military as a whole is at DEFCON 2, that in of it self shouldn’t be alarming... Being in the War on Terror, I wouldn’t be surprised if we have been at it since 9/11/2001.