As successful as the F-100F undoubtedly was in the defence suppression role, the aircraft had a number of deficiencies and was only ever regarded as an interim platform to prove the Wild Weasel concept.  The F-100F had a poorer performance than the aircraft it was supposed to be protecting, the F-105D.  The strike aircraft had to weave from side to side in order not to overtake the Super Sabre.  The F-100F also had a more limited range and load carrying capability than the F-105.  In January 1966 it was decided to develop the F-4C and the F-105F for the Wild Weasel role.  Work on the F-105 was rapid and on the 15th of that month the first modified F-105F was flown.  The project was designated as Wild Weasel III and the aircraft was known as either the EF-105F or simply and more commonly as the F-105F Wild Weasel.  The F-105F carried the same electronic equipment as the F-100F plus the AZ-EL system that gave the azimuth and elevation bearing, and the SEE-SAMS(B) passive warning system (later replaced by the ALR-31) that gave an indication of an imminent SAM launch.

The first of 10 initial F-105F Wild Weasels arrived at Korat on 28 May but the F-100F flew on in the role until 11 July.  The F-105F Wild Weasel detachment was incorporated into the 13th TFS in July and gradually took over the Wild Weasel mission from the F-100F detachment, having achieved its first kill on 7 June.  On 5 July a Wild Weasel flight led by an F-105F attacked and damaged four SAM sites but the very next day the first F-105F was lost along with its crew.  A month later another F-105F detachment was formed, this time at Takhli under the 354th TFS.  Initially at least, the 388th TFW concentrated all its Weasels under the 13th TFS while the 355th TFW spread the aircraft around its three squadrons.