BUD meaning in Military and Defence ?

The United States Navy Sea, Air, and Land (SEAL) Teams, commonly known as Navy SEALs, are the U.S. Navy's primary special operations force and a component of the Naval Special Warfare Command. Among the SEALs' main functions are conducting small-unit special operation missions in maritime, jungle, urban, arctic, mountainous, and desert environments. SEALs are typically ordered to capture or to eliminate high level targets, or to gather intelligence behind enemy lines.

All active SEALs are male and members of the U.S. Navy. The CIA's highly secretive and elite Special Operations Group (SOG) recruits operators from SEAL Teams, with joint operations going back to the MACV-SOG during the Vietnam War. This cooperation still exists today, as evidenced by military operations in Iraq and Afghanistan.