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170 FIGHTING THE ELECTRONIC WAR
in the benefits to be derived from tapping Soviet and Satellite
landlines on a scale not previously considered necessary. The
loss of certain sources during this period created gaps in our
intelligence coverage which were particularly unfortunate during
this period of Cold War escalation.' By tapping into telephone
lines, the West hoped to pick up sensitive voice traffic that the
Soviets were not troubling to encrypt, because unlike messages
sent by radio transmitter, underground landlines were thought
to be inaccessible and therefore secure. 2
The idea of tapping phone lines in Vienna and Berlin mirrored
existing activities by the KGB. As early as October 1946, the
British Control Commission in Germany had reviewed the
twenty-two 'secrephones' or scrambler phones installed in Berlin
for communication with the British Zone of Germany, and had
found them wanting. The encypherment provided by the scrambler
was weak, and with the telephone lines passing through
the Soviet Zone, they were presumed to be tapped. Even within
the British Zone, the military had been anxious about allowing
Germans who worked in telephone exchanges to have access
to military telephone directories, since this would give them a
'comprehensive guide to the most profitable extensions on which
to listen in'. Only specially screened Germans were put to work
in the telephone exchanges. 3
Poor telephone security had the potential to blow high-grade
British cyphers. For example, it had long been known that the
direct telephone line between the British element of the Allied
Commission for Austria and London was monitored by the
Soviets, and in early February 1948 British intelligence had
discovered that they were 'strengthening their interception
arrangements'. The problem was that although officials in the
British headquarters in Vienna were given continual security
warnings, the officials they were talking to in London were less
diligent. Frequently, telephone conversations were about
agreeing the final text of a document, which was then sent by
telegram in a high-grade cypher. For the Soviet code-breakers
this was a gift, since they now had both the encyphered text