The Department of Defense announced today (Sunday) the death of a sailor who was supporting Operation Enduring Freedom. Petty Officer 1st Class (SEAL) Caleb A. Nelson, 26, of Omaha, Neb.,died after his vehicle struck an improvised explosive device while conducting a combat patrol in Zabul province, Afghanistan on Oct.1.  Nelson was assigned to an East Coast-based Naval Special Warfare unit, Norfolk, Va.