Despite the difficulties encountered in integrating north and south, the most important political issue in postindependence Somali politics was the unification of all areas populated by Somalis into one country--a concept identified as pan-Somalism, or Greater Somalia. Politicians assumed that this issue dominated popular opinion and that any government would fall if it did not demonstrate a militant attitude toward neighboring countries occupying Somali territory.

Preoccupation with Greater Somalia shaped the character of the country's newly formed institutions and led to the build-up of the Somali military and ultimately to the war with Ethiopia and fighting in the NFD in Kenya. By law the exact size of the National Assembly was not established in order to facilitate the inclusion of representatives of the contested areas after unification. The national flag featured a five-pointed star whose points represented those areas claimed as part of the Somali nation--the former Italian and British territories, the Ogaden, Djibouti, and the NFD. Moreover, the preamble to the constitution approved in 1961 included the statement, "The Somali Republic promotes by legal and peaceful means, the union of the territories." The constitution also provided that all ethnic Somalis, no matter where they resided, were citizens of the republic. The Somalis did not claim sovereignty over adjacent territories, but rather demanded that Somalis living in them be granted the right to self-determination. Somali leaders asserted that they would be satisfied only when their fellow Somalis outside the republic had the opportunity to decide for themselves what their status would be.

At the 1961 London talks on the future of Kenya, Somali representatives from the NFD demanded that Britain arrange for the NFD's separation before Kenya was granted independence. The British government appointed a commission to ascertain popular opinion in the NFD on the question. Its investigation indicated that separation from Kenya was almost unanimously supported by the Somalis and their fellow nomadic pastoralists, the Oromo. These two peoples, it was noted, represented a majority of the NFD's population.

Despite Somali diplomatic activity, the colonial government in Kenya did not act on the commission's findings. British officials believed that the federal format then proposed in the Kenyan constitution would provide a solution through the degree of autonomy it allowed the predominantly Somali region within the federal system. This solution did not diminish Somali demands for unification, however, and the modicum of federalism disappeared after Kenya's government opted for a centralized constitution in 1964.

The denial of Somali claims led to growing hostility between the Kenyan government and Somalis in the NFD. Adapting easily to life as shiftas, or bandits, the Somalis conducted a guerrilla campaign against the police and army for more than four years between 1960 and 1964. The Somali government officially denied Kenya's charges that the guerrillas were trained in Somalia, equipped there with Soviet arms, and directed from Mogadishu. But it could not deny that the Voice of Somalia radio influenced the level of guerrilla activity by means of its broadcasts beamed into Kenya.

Somalia refused to acknowledge in particular the validity of the Anglo-Ethiopian Treaty of 1954 recognizing Ethiopia's claim to the Haud or, in general, the relevance of treaties defining Somali-Ethiopian borders. Somalia's position was based on three points: first, that the treaties disregarded agreements made with the clans that had put them under British protection; second, that the Somalis were not consulted on the terms of the treaties and in fact had not been informed of their existence; and third, that such treaties violated the self-determination principle.

Incidents began to occur in the Haud within six months after Somali independence. At first the incidents were confined to minor clashes between Ethiopian police and armed parties of Somali nomads, usually resulting from traditional provocations such as smuggling, livestock rustling, and tax collecting, rather than irredentist agitation. Their actual causes aside, these incidents tended to be viewed in Somalia as expressions of Somali nationalism. Hostilities grew steadily, eventually involving small-scale actions between Somali and Ethiopian armed forces along the border. In February 1964, armed conflict erupted along the Somali-Ethiopian frontier, and Ethiopian aircraft raided targets in Somalia. Hostilities ended in April through the mediation of Sudan, acting under the auspices of the Organization of African Unity (OAU). Under the terms of the cease-fire, a joint commission was established to examine the causes of frontier incidents, and a demilitarized zone ten to fifteen kilometers wide was established on either side of the border. At least temporarily, further military confrontations were prevented.

Ethiopia and Kenya concluded a mutual defense pact in 1964 in response to what both countries perceived as a continuing threat from Somalia. This pact was renewed in 1980 and again on August 28, 1987, calling for the coordination of the armed forces of both states in the event of an attack by Somalia. Most OAU members were alienated by Somali irredentism and feared that if Somalia were successful in detaching the Somali-populated portions of Kenya and Ethiopia, the example might inspire their own restive minorities divided by frontiers imposed during the colonial period. In addition, in making its irredentist claims, the Somalis had challenged two of Africa's leading elder statesmen, President Jomo Kenyatta of Kenya and Emperor Haile Selassie of Ethiopia.