The same was not true for the data handling portion of the Linesman system, which faced repeated delays and only entered minimal operation on 18 December 1973. It was officially handed over to Strike Command on 1 February 1974 and declared in-service on 31 March. By that time it was already considered obsolete; some of the smaller supplier companies were no longer in the computer business and the germanium transistors used in the Plessy computers were no longer produced. Even its programmers suggested none of it actually worked, and the RAF itself finally reported that it was "so obsolete, it could not cope with any air threat." When Linesman was first being considered the belief was that any war in Europe would be nuclear, and that any air attack on England would be as well. In this environment, there was no point trying to harden command centres, they would be destroyed if attacked. This led to the main control center, L1, being moved to an aboveground office building near Heathrow Airport. Fighter Command repeatedly protested, noting that the entire air defence network might be taken out by an explosive truck on the road outside the building or jamming of the microwave links that fed it. They repeatedly called for command to be devolved to the radar stations, as it had been in the Type 80 era. Moreover, the strategic situation changed once again. As the Soviets gained strategic parity with the US, the idea of meeting any Warsaw Pact offence with tactical nuclear weapons was no longer seen as a safe response as the US was now just as deterred from using their strategic forces as the Soviets had been formerly. Additionally, new weapons like the TOW missile fired from attack helicopters appeared to offer an all-conventional method of defeating the Pact. Now it appeared war in Europe would have a long conventional phase, and air attack on England was likely yet unlikely to be nuclear. This was especially true in light of newer long-range Soviet aircraft that could approach the UK at low level and thereby avoid detection altogether. Studies of a replacement system started in 1972, and multiple reports were produced on the topic over the next year. They proposed using modern commercial computers in place of the specialized systems of Linesman, adding complete digitization of all signals from all radars in the network, upgrading links to their counterparts in NADGE, which were at that time forwarded over voice lines, and devolving command to new hardened CRC centers, remote from the radar sites. L1 would remain in use, but primarily to disseminate information outside of Strike Command and to build the nationwide Recognized Air Picture.