Final answer:
The Gouzenko affair set a tone of fear and suspicion in Canada, contributing to the start of the Cold War.
Step-by-step explanation:
The Gouzenko affair, also known as the Gouzenko spy case, set a tone of heightened fear and suspicion in Canada.
It refers to a 1945 incident in which Igor Gouzenko, a Soviet cipher clerk, defected from the Soviet Embassy in Ottawa and exposed evidence of Soviet espionage activities in Canada.
This affair heightened tensions between Canada and the Soviet Union and contributed to the start of the Cold War.