Despite the passport union with Sweden, Norway, Denmark, and Iceland, Finland could not join the Nordic Council until 1955 because of Soviet fears that Finland might become too close to the West. At that time the Soviet Union saw the Nordic Council as part of NATO of which Denmark, Norway and Iceland were members. That same year Finland joined the United Nations, though it had already been associated with a number of UN specialized organisations. The first Finnish ambassador to the UN was G.A. Gripenberg (1956–1959), followed by Ralph Enckell (1959–1965), Max Jakobson (1965–1972), Aarno Karhilo (1972–1977), Ilkka Pastinen (1977–1983), Keijo Korhonen (1983–1988), Klaus Törnudd (1988–1991), Wilhelm Breitenstein (1991–1998) and Marjatta Rasi (1998–2005). In 1972 Max Jakobson was a candidate for Secretary-General of the UN. In another remarkable event of 1955, the Soviet Union decided to return the Porkkala peninsula to Finland, which had been rented to the Soviet Union in 1948 for 50 years as a military base, a situation which somewhat endangered Finnish sovereignty and neutrality.. Which Finnish ambassadors to the UN served 6 year terms?