With the late 1965 introduction of the S-75 (SA-2) surface to air missile system in North Vietnam, the US Air Force began looking for methods to counter this deadly threat to its strike forces. Locating and suppressing batteries of SAMs was a challenging role, hampered not just by the difficulty of the mission, but by poor equipment. Two seat F-100F fighters were the first platform used. But they had virtually no sensors beyond the human eyeball. The F-100 also had limited range and payload. The crews of these SAM hunters lacked almost everything but sheer guts. They cheerfully took on the role of attacking not just into the teeth of the enemy’s defenses, but the very defenses themselves. This “in your face” boldness led them to name themselves the Wild Weasels. Their motto, YGBSM, similarly noted their valor.
Soon after they began operations, the need for more range and payload, and room for growth for sensors lead the Air Force to assign the Wild Weasels the F-105F two-seat operational trainer version of the Thud. Of 143 “F” models built, eventually 54 were converted to EF-105F* configuration. Added Radar Homing and Warning devices and receivers allowed these Wild Weasels to locate, triangulate, and range the location of SAM sites based on the transmissions of their search and fire control radars.
Even more useful, the EF-105F added the AGM-45 Shrike anti-radiation missile to the available weapons. The Shrike, modified from the design of the AIM-7 Sparrow III missile, had a passive seeker that homed in on the fire control radar of the SA-2. Vietnamese radar operators could avoid the Shrike by shutting down their radar, but while that radar was down, the Weasel crews could close in and attack with conventional bombs and cluster munitions. More importantly, while the SAM site was suppressed, the main body of a strike force could carry out their mission unmolested by SAMs.
Further improvements to the “F” led to the F-105G** which served as the Air Force’s primary Suppression of Enemy Air Defenses (SEAD) platform until replaced by the F-4G Advanced Wild Weasel. The F-4G was replaced shortly after Desert Storm by the F-16CJ Wild Weasel.
*Not an official designation, it was still handy to differentiate them from vanilla two-seater Thuds.
**This time an official designation.