Why is the Petrov Affair considered an important event in Australia's response to the threat of communism?

The Petrov Affair reflected the extent of concern
regarding the possibility of Soviet espionage in Australia and highlighted the
conflicting responses to that concern, and to Communism in general, among members of the
Australian government.

The timing of Vladimir Petrov's
defection, shortly before the 1954 elections, gave Liberal Party member and Prime
Minister Menzies the opportunity to present a strong anti-Communist stand as he
coordinated the seizure of Evdokia Petrov away from Soviet officials before she could be
returned to the Soviet Union after her husband's defection. Menzies claimed that the
Petrovs provided documents revealing an extensive Communist spy ring in Australia,
including Dr. H. V. Evatt, a well-respected official and Labor Party candidate for Prime
Minister. Evatt's conduct during investigations reflected his view that the Liberal
government had intended to use the defections to its advantage during the election
campaign and that he felt personally as well as politically threatened. The Labor Party,
which had been expected to win the elections, lost as Menzies was reelected.
Anti-Communist sentiment was heightened by the entire affair, even within the Labor
Party, which splintered due to varied reactions to Evatt's statements and
actions.