In September 1962, a civil war broke out in Yemen. It contained the seeds of a wider conflict because of the involvement of Saudi Arabia and the United Arab Republic (Egypt). Saudi Arabia shared an extended border with Yemen and much of it was still undefined. The United Arab Republic had maintained a special relationship with Yemen in the past. (In March 1958, Yemen and the United Arab Republic had formed the United Arab States. However, the association was dissolved in December 1961.) A further factor in the situation was that Yemen had long claimed that the Aden Protectorate was legally part of its territory. Accordingly, the British-controlled government of the South Arabian Federation, which included the Aden Protectorate, also closely followed developments in Yemen.

On September 19, 1962, Imam Ahmed bin Yahya died and was succeeded by his son, Imam Mohammed Al-Badr. A week later, a rebellion led by the army overthrew the new Imam and proclaimed the Yemen Arab Republic. The new government was recognized by the United Arab Republic on September 29th and by the Soviet Union the next day. Other major powers including the United Kingdom and the United States withheld action on the question of recognition.

Following his overthrow, Imam Al-Badr managed to escape from San'a, the capital of Yemen. With other members of the royal family, he rallied the tribes in the northern part of the country. With financial and material support from external sources, the royalists fought a fierce guerrilla campaign against the new government. The new government accused Saudi Arabia of harboring and encouraging the Yemeni royalists and threatened to carry the war into Saudi Arabian territory. The Imam claimed that the original army rebellion had been fostered and aided by the United Arab Republic, which denied the charge. At the beginning of October, large numbers of United Arab Republic forces were dispatched to Yemen at the request of the revolutionary government to assist in their fight against the royalists.

On November 27th, the Permanent Mission of Yemen to the United Nations requested that the United Nations conduct an inquiry to ascertain whether the army rebellion had been supported by the United Arab Republic. The Permanent Mission was still staffed by royalists. A delegation from the new Yemeni government, which had arrived in New York by that time, indicated that they would not object to a United Nations investigation. Subsequently, the General Assembly decided to only recognize the credentials of the new government.

On May 27, 1963, Secretary-General U Thant concluded that UN observers should be sent to Yemen. Accordingly, on June 11th, the Security Council adopted resolution 179 which established the United Nations Yemen Observation Mission (UNYOM). UNYOM was primarily composed of six military observers, a Yugoslav reconnaissance unit of 114 personnel and a Canadian air unit. In addition, 28 international staff members and a small military staff were assigned to UNYOM headquarters. The military observers were detailed from UNTSO and the reconnaissance unit personnel were drawn from the Yugoslav contingent of the United Nations Emergency Force (UNEF), which had experience in United Nations peacekeeping operations in similar terrain. The UNEF air base at El Arish provided support for the Canadian air unit, and included six aircraft and a similar number of helicopters.

The Secretary-General appointed General von Horn of Sweden as Commander of UNYOM. With the arrival of General von Horn and the first group of military personnel, UNYOM began operations on July 4, 1963. The mandate of UNYOM stemmed from the disengagement agreement entered into by Saudi Arabia, the United Arab Republic and the Arab Republic of Yemen. The function and authority of UNYOM as defined in the agreement were considerably more limited than in the case of other United Nations observation missions. For example, its establishment was not based on any cease-fire agreement and there was no cease-fire to supervise. The tasks of UNYOM were limited strictly to observing, certifying and reporting in connection with the intention of Saudi Arabia to end activities in support of the royalists in Yemen and the intention of Egypt to withdraw its troops from that country.

On September 2, 1964, the Secretary-General submitted his final report on UNYOM. In it, he acknowledged the failure of the parties to implement the disengagement agreement and the difficulties UNYOM faced in observing and reporting on these matters. While there had been a substantial reduction in the strength of the Egyptian forces in Yemen, the withdrawal was a reflection of the improvement in the situation of the Yemeni republican forces rather than the beginning of a phased withdrawal. There were also indications that the Yemeni royalists had continued to receive military supplies from external sources. Noting that UNYOM had been able to observe only limited progress towards the implementation of the agreement, U Thant reiterated his view that UNYOM's terms of reference were restricted to observation and reporting only and that the responsibility for implementation lay with the two parties to the agreement. He stated that UNYOM had made significant accomplishments and that the mission had exercised an important restraining influence on hostile activities in the area. On September 4, 1964, the activities of UNYOM ended and its personnel and equipment were withdrawn.

From The Blue Helmets: A Review of United Nations Peace-keeping. Copyright 1990 United Nations. Published by United Nations Department of Public Information.