Defense Health Agency. The Defense Health Agency (DHA) is a joint, integrated Combat Support Agency that enables the U.S Army, U.S Navy, and U.S Air Force medical services to provide a medically ready force and ready medical force to Combatant Commands in both peacetime and wartime.
Definition of preemption. 1a : the right of purchasing before others; especially : one given by the government to the actual settler upon a tract of public landb : the purchase of something under this right.
Preempt is a bid in contract bridge whose primary objectives are to thwart opponents ability to bid to their best contract, with some safety, and to fully describe one's hand to one's partner in a single bid. A preemptive bid is usually made by jumping, i.e. skipping one or more bidding levels.