As part of the “Prevention Through Deterrence” strategy, which called for reducing unauthorized migration by placing agents and resources directly on the border abutting population centers, in 1990 the USBP began erecting a physical barrier to deter illegal entries and drug smuggling in the San Diego sector using the broad powers granted to the Attorney General (AG) to control and guard the U.S. border. The ensuing “primary” fence was completed in 1993 and covered the first 14 miles of the border, starting from the Pacific Ocean, and was constructed of 10-foot-high welded steel. This fence (and the subsequent three-tiered fence, see discussion below) was constructed with the assistance of the Department of Defense’s (DOD’s) Army Corps of Engineers