I think that colonel was actually the CJCS (played by George C. Scott) in the movie.
“....George C. Scott played the role of General Buck Turgidson, the Chairman of the Joint Chiefs of Staff. ....”
https://en.wikipedia.org/wiki/Dr._Strangelove#George_C._Scott_as_General_Buck_Turgidson
The guy who ordered the preemptive strike was Gen. Jack Ripper (Sterling Hayden). After Slim Pickens rode the bomb, Turgidson wanted all the other B52s to strike Russia, but the Doomsday Machine was already started.
Nope, I was wrong about the rank, but it wasn’t George C. Scott. From Wiki, it was Sterling Hayden’s character who ordered the Air Force bomber wing to attack the USSR to stop them from putting fluoride in our water.