I was skimming through Bernard C. Nalty's USAF Ballistic Missile Programs, March 1967, and came across this interesting information concerning the Titan II system. The entire volume of work can be viewed here and also via the NSA Archives site. (Bold faced emphasis by post writer.)
In light of the forthcoming retirement of Titan II, the Air Force was reluctant to spend large amounts to protect the system's Mk-6 reentry vehicle against nuclear detonation effects. Although a $50 to $60 million hardening program of this type was disapproved, the Air Force did proceed with two projects to protect the Titan launch complexes. They were Yard Fence and Loggy Ebb, originally called Low Ebb. Begun in 1965, Yard Fence was aimed at improving the reliability of equipment installed at Titan II sites. Work done under this program included adding. neutron shielding and acoustical lining and fitting new seals around blast doors. The project was to have been completed in the spring of 1966, but a silo fire near Searcy, Ark., in 1965 killed 53 civilian workers and compelled the Air Force to suspend work.and...
Loggy Ebb, the other major project, was designed to provide protection against electromagnetic pulse, an effect of nuclear explosions that could damage vital electrical equipment. During the summer of 1967 workers at Little Rock began installing surge arrestors to protect Titan II circuits, generators, and buried cables. USAF plans called for completion of Loggy Ebb in October 1968 at Davis-Monthan AFB.Of interest is the fact that work on the Titan II sites, for Loggy Ebb, started during the summer of 1967 possibly in conjunction with SAC's directives to install EMP filters/suppressors in the Minuteman I and II weapon systems. Loggy Ebb was more than likely already in the engineering and planning phase the year prior to Echo Flight's shutdown, but could the project have been expedited due to Echo's ten missile shutdown? At a minimum, programs such as Loggy Ebb, demonstrates that the Air Force, SAC and DOD were cognizant of the growing vulnerabilities of the entire ICBM force to the effects of EMP.
I have provided the link to the Engineering Change Proposal (ECP) , HIC EM Pulse Suppressor, for fixing the EMP issues effecting the Minuteman system. Note that the ECP is marked "routine" at the top, line 2, for Boeing's recommended priority. Boeing appeared not to be in "panic" mode to rush out a quick fix.