expansion of parliament it won an additional seat. In 1956 the party supported the Russian intervention against the Hungarian revolution. After the invasion, the party office, in Felix Meritis in Amsterdam, was attacked by opponents of the invasion. Meanwhile, internal dissent against the strict leadership of De Groot was rising. In 1958 the Bruggroep ("Bridge group") left the CPN in a conflict over the role of the Communist Eenheidsvakcentrale (Unity Trade Union). Leaders of the Bruggroep were prominent Resistance figures like Gerben Wagenaar and Henk Gortzak. The Dutch secret service (AIVD) claimed to be behind the split, while the CPN leadership claimed that the dissenters were agents working for the U.S. Central Intelligence Agency. The Bruggroep founded a new party, the Socialistische Werkers Party (Socialist Workers' Party, SWP). In 1957 the Pacifist Socialist Party was founded. The PSP united former members of the CPN, including members of the Socialist Union, and the Dutch Labour Party (PvdA), and other leftwing independents. In the following 1959 elections the CPN lost all but three seats, while the PSP won two seats, and the SWP was unable to win any seats. Many SWP members, like Gortzak, later joined the PSP. In the 1940s and 1950s the CPN was methodically isolated by other parties. Civil servants were forbidden to become members of the CPN and it was not allowed separate time on public radio or television. The party's unequivocal support for decolonization of the Dutch East Indies isolated the party in parliament. Because of its anti-NATO and European Economic Community stances the party was blocked from the Foreign Affairs, Defense, and Nuclear Energy committees in parliament. The AIVD kept close tabs on the party. All other parties in parliament were deeply anti-Communist, especially the social-democratic PvdA. In the 1963 elections the party gained one seat. The developing students' movement was an important impetus for the party. In 1964, the international conflict between the People's Republic of China and the USSR also split the CPN. A group called Communist Unity Movement of the Netherlands left the CPN in that year. They went through several intense splits based on ideological and personal conflicts. In 1971 one of the small groups formed the Socialist Party, which became a successful political party from the mid-1990s. The CPN took a rather ambiguous stance in the conflict between the USSR and the PRC. 1967–1989 Before the 1967 elections De Groot was