the 3970th Strategic Wing on 25 June 1966. The 98th SW was inactivated at Lincoln Air Force Base Nebraska that same day with the closure of Lincoln AFB. The 98th SW had no permanently assigned aircraft assigned, however CONUS-based SAC wings deployed aircraft to provide air refueling sup-port to meet the operational, alert, and exercise commitments of SAC, TAC, USAFE, and NATO in an area including the eastern Atlantic, most of Europe, North Africa and the Middle East. Even though neither were assigned to the base, when a B-52 and a KC-135 crashed off the coast of Spain in the 1966 Palomares B-52 crash, Torrejón became the focal point for the search for the missing nuclear weapons. Military Airlift Command (MAC) operated the 625th Military Airlift Support Squadron at Torrejón to function as a major terminal for MAC transatlantic flights. In 1970 the 401st TFW upgraded to the McDonnell Douglas F-4E Phantom II. In September 1973, an equipment change to the F-4C model took place, then in 1979 to the F-4D. As a result of the withdrawal of USAF forces in South Vietnam, on 15 July 1971 the 307th and 353rd TFS were returned to their home bases, and the 612th and 614th TFSs were assigned to Torrejón. Also in 1972, individual squadron tail codes were eliminated and "TJ" became the tail code for all 401st TFW aircraft. On 31 December 1976 the 98th Strategic Wing was inactivated with its air refueling mission being taken over by the 306th Strategic Wing, based at Ramstein Air Base, West Germany. The 401st transitioned to the new General Dynamics Block 15 F-16A/B Fighting Falcon beginning with the first aircraft deliveries on 5 February 1983. The wing reached full F-16 operational capability on 1 January 1985. The F-16A/B models were upgraded to the Block 30 F-16C/D beginning in late 1987, with all aircraft replaced by September 1988. Operational squadrons were: 612th Tactical Fighter Squadron (blue tail stripe) 613th Tactical Fighter Squadron (yellow tail stripe) 614th Tactical Fighter Squadron (red tail stripe) USAF withdrawal As the time approached in 1987 for the renegotiation of the existing base agreement, which had entered into force in 1983 for a five-year period, pressures mounted for a reduction of the United States military presence in Spain. Communist political groups and elements of the Spanish Socialist Workers' Party (PSOE) had campaigned against the bases. Moreover, the base agreement had become