ALTHOUGH Moscow AND Pyongyang have a mutual defense treaty, a common ideology, and extensive economic and military relations, the relationship between the two communist powers has been seriously troubled ever since the late 1950s. At that time, Kim Il-song, after a series of purges, was able to assert his leadership against a rival group of leaders whom Kim subsequently accused of trying to subvert him with Russian assistance.' By 1958, Kim, who had been lifted from obscurity and installed in power by Russian troops during the Soviet occupation of the northern part of Korea at the end of World War II, had created an independent power base, overcome the last remnants of internal opposition, and asserted his independence from both Moscow and Peking. Since the early 1960s, Soviet relations with North Korea have moved through three stages, all of them connected primarily with the Sino-Soviet conflict and Moscow's determination to line Pyongyang up on its side of that historic dispute. Between 1962 and 1964, Soviet Premier Khrushchev, who was not reputed for his subtlety, was determined to apply maximum pressure on the Chinese. He was therefore unwilling to tolerate any waverers on the issue from within the socalled socialist camp. Because Kim Il-song was unwilling to line up with Khrushchev on the China issue, relations between Moscow and Pyongyang deteriorated to a point where Khrushchev cut economic assistance to Pyongyang and North Korea publicly accused the Russians of big power chauvinism, xenophobia, and exploitations Immediately after Khrushchev's removal, the new Soviet leaders sought to make the energetic Soviet premier a scapegoat for their difficulties with both Peking and Pyongyang and to improve relations