In 1969, in response to demands for a capable night interdiction aircraft for combat operations in the Vietnam theatre, a total of 16 B-57B Canberras were substantially rebuilt during a lengthy upgrade program. These aircraft received an entirely new nose section containing an AN/ANQ-139 forward-looking radar, a low-light television system, and an AN/AAS-26 forward-looking infrared detector. A laser rangefinder/designator was also installed, and the wing pylons modified to accommodate laser-guided Paveway bombs, while all the guns were removed to save weight. During the production run from 1953 to 1957, a total of 403 B-57s were built.