The pattern of U.S. trade expansion followed by trade restrictions also appears to have characterized U.S.-Soviet economic relations, not only for the past three decades, but plausibly since the 1920s. Unlike earlier fluctuations, however, recent cycles have been occurring more rapidly and lasting a shorter period of time. The pro-trade period of detente existed for approximately five years from 1969 to 1974 before it began to erode. The strongest period of pro-control sentiment extended also for five years, from 1979 to 1984... When... expectations were disappointed, there was a tendency to view the Soviet Union as acting "in bad faith," lending support to conservative, pro-control forces.