By the 1960s the party's membership had fallen to around 5,000, but it continued to hold positions in a number of trade unions, and it was also influential in the various protest movements of the period, especially the movement against the Vietnam War. During this period, the party became more openly critical about the Soviet Union and the Communist Party of the Soviet Union. In 1966, the party started their own magazine called Australian Left Review. In 1967, the party ceased receiving payments from the Communist Party of the Soviet Union following a seminar by Laurie Aarons in the Soviet Union which argued that "ideas require free contest, not confined in a framework of established dogmas that can become a rigid or even ossified edifice". But the Soviet invasion of Czechoslovakia in 1968 triggered another crisis. Sharkey's successor as party leader, Laurie Aarons, denounced the invasion, and a group of pro-Soviet hardliners left in 1971 to form a new party, the Socialist Party of Australia.