Why is DHS buying 2500 armored fighting vehicles and 2 billion rounds of ammo?

WHY IS THE DEPARTMENT OF HOMELAND SECURITY BUYING SOME 2 BILLION ROUNDS OF AMMO. 

ROUNDS THAT ARE ILLEGAL FOR THE MILITARY TO  USE UNDER THE GUIDELINES LAYED DOWN BY THE GENEVA CONVENTION.  AMMO THAT CAN ONLY BE USED AGAINST CIVILIANS.  WHAT IS DHS UP TOO?

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