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280 TURBULENCE AND TERROR
information, which had probably not been passed to us
over intelligence channels, was of peculiar delicacy.7
*
Although Kissinger felt the 'intercept was insufficient evidence
to form a judgement on Soviet intention', he was clearly excited.
At the same time, his powerful realist instincts pushed him
towards the view that greater military pressure on Hanoi over
the coming months would make the North Vietnamese more
responsive at the negotiating table. s
Kissinger's conflicting thoughts about the Firyubin intercept
underlined the limitations of Western sigint in the early 1970s.
Sigint - and indeed imagery - was delivering fabulous information
on Soviet technical and military activity. Supplemented
by widespread bugging, it also offered superb insights into diplomatic
exchanges at conferences outside Russia, when diplomats
were vulnerable to short-range interception. The British had,
for example, achieved excellent coverage of Alexei Kosygin, the
Soviet Premier, during his recent stay at Claridge's Hotel in
London. 9 Sigint was especially valuable against the leadership
of North Vietnam, and offered useful insights into negotiations
with Hanoi during the late 1960s and early 1970s. Yet the innermost
thoughts of the Moscow leadership remained elusive. More
than two decades after Black Friday, Soviet high-level diplomatic
communications remained largely unreadable.
Indiscretions by Soviet diplomats like Nikolay Firyubin on their
travels offered only a fleeting glimpse of the thinking of the
Politburo. 1O
Some joint Anglo-American intelligence operations were
attempting to lift the corner of this veil of secrecy. There had
been considerable success in intercepting Soviet government
telephone calls, which were carried by microwave relay systems.
Much of this material was acquired at short range by technical
teams in the British and American Embassies in Moscow. The
British operation was code-named 'Tryst', and the American
was 'Broadside'. In 1972 the Canadians joined them with their
own sigint operation, 'Stephanie'. However, American journal-