U Thant's approach to his office was different from that of Hammarskjöld, whose dynamic conception of the secretary-general's political role had aroused such opposition in the Soviet bloc. Thant did not take the same initiatives as his predecessor, but he consistently sought to use the prestige of his office to help settle disputes. Moreover, both the General Assembly and the Security Council assigned him to mediate extremely delicate situations. In his annual reports, he put forth proposals on basic issues, such as disarmament and economic and social cooperation and many of his suggestions were adopted.
An early example of a successful initiative taken by U Thant was in connection with the long-standing dispute between Indonesia and the Netherlands over the status of West Irian. The territory, formerly known as West New Guinea, had belonged to the Dutch East Indies, and Indonesia now claimed it as its own. In December 1961, fighting broke out between Dutch and Indonesian troops. Appealing to both governments to seek a peaceful solution, the secretary-general helped them arrive at a settlement. That settlement, moreover, brought new responsibilities to the office of the secretary-general: for the first time in UN history, a non-self-governing territory was, for a limited period, administered directly by the world organization.
The Cyprus Operation. Intercommunal clashes broke out in Cyprus on Christmas Eve 1963 and were followed by the withdrawal of the Turkish Cypriots into their enclaves, leaving the central government wholly under Greek Cypriot control. A "peace-making force" established under British command was unable to put an end to the fighting, and a conference on Cyprus held in London in January 1964 ended in disagreement. In the face of the danger of broader hostilities in the area, the Security Council on 4 March 1964 decided unanimously to authorize U Thant to establish a UN Peacekeeping Force in Cyprus (UNFICYP), with a limited three-month mandate to prevent the recurrence of fighting, to help maintain law and order, and to aid in the return to normal conditions. The force was to be financed on the basis of voluntary contributions. The Council also asked the secretary-general to appoint a mediator to seek a peaceful settlement of the Cyprus problem. The report of U Thant's mediator, Galo Plaza Lasso, was transmitted to the Security Council in March 1965 but was rejected by Turkey. Plaza resigned in December 1965, and the function of mediator lapsed.
Another crisis occurred in November 1967, but threatened military intervention by Turkey was averted, largely as a result of US opposition. Negotiations conducted by Cyrus Vance for the US and José Rolz-Bennett on behalf of the secretary-general led to a settlement. Intercommunal talks were begun in June 1968, through the good offices of the secretary-general, as part of the settlement. The talks bogged down, but U Thant proposed a formula for their reactivation under the auspices of his special representative, B. F. Osorio-Tafall, and they were resumed in 1972, after Thant had left office.
The India-Pakistan War of 1965 and Conflict of 1971. Hostilities between India and Pakistan broke out in Kashmir in early August 1965 and soon spread along the entire length of the international border from the Lahore area to the sea. At the behest of the Security Council, whose calls on 4 and 6 September for a cease-fire had gone unheeded, U Thant visited the subcontinent from 9 to 15 September. In his report to the Council, the secretary-general proposed certain procedures, including a possible meeting between President Ayub of Pakistan and Prime Minister Shastri of India, to resolve the problem and restore the peace.
The Council, on 20 September, demanded a cease-fire and authorized the secretary-general to provide the necessary assistance to ensure supervision of the cease-fire and withdrawal of all armed personnel. For this purpose, U Thant strengthened the existing UN Military Observer Group in India and Pakistan (UNMOGIP), stationed in Kashmir, and established the UN India-Pakistan Observation Mission (UNIPOM) to supervise the cease-fire and withdrawal of troops along the border outside Kashmir.
At a meeting organized by Soviet Premier Kosygin in January 1966 in Tashkent, USSR, the leaders of India and Pakistan agreed on the withdrawal of all troops; this withdrawal was successfully implemented under the supervision of the two UN military observer missions in the area. UNIPOM was disbanded in March 1966, having completed its work.
Following the outbreak of civil strife in East Pakistan in March 1971 and the deterioration of the situation in the subcontinent that summer, U Thant offered his good offices to India and Pakistan and kept the Security Council informed under the broad terms of Article 99 of the Charter. When overt warfare broke out in December, the Security Council appealed to all parties to spare the lives of innocent civilians. Pursuant to a decision by the Council, U Thant appointed a special representative to lend his good offices for the solution of humanitarian problems after the cease-fire of 18 December 1971, which was followed by the independence of Bangladesh.
U Thant's Stand on the Vietnam War. Throughout his tenure, U Thant was deeply concerned with the question of Vietnam. By tacit consent, the question was never formally debated in the General Assembly and only cursorily touched upon in the Security Council. Until the opening of the Paris peace talks in 1968, the secretary-general was unremitting in his efforts to persuade the parties in the conflict to initiate negotiations on their own. In 1966, he put forward a three-stage proposal to create the conditions necessary for discussion, but it was ignored by the US.
After the Paris talks began, U Thant deliberately refrained from making any public statements on Vietnam "in order to avoid creating unnecessary difficulties" for the parties. He broke this silence only once, on 5 May 1970, when he expressed his deep concern "regarding the recent involvement of Cambodia in the war."
U Thant's Second Term. U Thant's second term of office was dominated by the protracted Middle East crisis that arose in the aftermath of the Six-Day War in 1967. His quick action in removing UNEF troops from the Suez area at the request of the United Arab Republic just before that war began occasioned much criticism and some misunderstanding.
Of the two other major political conflicts during the period 1967–70, the civil war in Nigeria and the Soviet invasion of Czechoslovakia on 20 August 1968, only the latter was debated at the UN. The political aspects of the Nigerian situation were never raised in either the General Assembly or the Security Council out of deference to the African countries themselves, whose main objective was to keep external intervention to a minimum. However, as the troops of the Federal Republic of Nigeria began to penetrate more deeply into the eastern region (which had announced its secession from Nigeria and proclaimed itself an independent state under the name of Biafra), the various humanitarian organs of the UN became increasingly concerned about the plight of the people there. Accordingly, in August 1968, the secretary-general took the initiative of sending a personal representative to Nigeria to help facilitate the distribution of food and medicine.
At the request of its six Western members, the Security Council decided to debate the situation in Czechoslovakia, despite the protests of the USSR. On 23 August 1968, 10 members voted for a resolution condemning the Soviet action, which the USSR vetoed. Another resolution, requesting the secretary-general to send a representative to Prague to seek the release of imprisoned Czechoslovak leaders, was not put to a vote. In view—as one UN text puts it—of the "agreement reached on the substance of the problem during the Soviet-Czechoslovak talks held in Moscow from August 23 to 26," no further action was taken by the Council. However, it is worth noting that U Thant was among the first world figures to denounce the invasion publicly. At a press briefing on 21 August at UN headquarters, he expressed unequivocal dismay, characterizing the invasion as "yet another serious blow to the concepts of international order and morality which form the basis of the Charter of the United Nations … and a grave setback to the East-West détente which seemed to be re-emerging in recent months."