Yemen's relations with neighboring states have often erupted in territorial conflicts. For example, in 1934 North Yemen's Imam Yahya was forced to cede the province of Asir to King Abd al-Aziz of Saudi Arabia. Tribal leaders in the area had allied with the king, and Yemeni government forces were not strong enough to enforce claims to the territory. Even though both the Yemeni Imam and the king of Saudi Arabia signed the Taif agreement settling the conflict, the eastern border of the region remained in question until 2000, when the two countries finally agreed on a definition of part of their border and set plans for marking the remainder of their border based on tribal considerations.
From the capital city, Sanaa, plateau lands stretch to the east and become increasingly arid until they finally merge with the great Rub' al-Khali, or Empty Quarter, of the Saudi Arabian desert. Borderlands originally demarcating South Yemen also stretch along the Arabian desert. After the discovery of oil and gas deposits, military clashes between Saudi Arabia and Yemen reignited. In general, Yemeni-Saudi relations improved in the late 1990's. These suffered a setback in 1998 when Saudi forces attacked Yemeni soldiers on Duwaima Island in the Red Sea. However, in June, 2000, the foreign ministers of the two countries signed a treaty based on the 1934 agreement. Although this new treaty established only part of the common border, it stated that the rest of the border would be drawn in a peaceful and friendly manner.
Yemen's strategic position at the tip of the Arabian Peninsula has also created conflicts. Yemen lies at the southern entrance to the Red Sea. Its ownership of two islands, Greater and Lesser Hanish, caused fighting during the 1990's. For centuries the two islands were considered a hazard to ships. Britain maintained lighthouses there even after it left Aden in 1967. Eventually Yemen took possession of the islands.
Eritrea, Yemen's neighbor across the Bab al-Mandab strait, claimed the islands as their own in 1993, when they became independent from Ethiopia. Yemen had supported Eritrea in its fight for independence, and nothing was done about the claim to the islands. In 1995 Eritrea moved to take over the islands and fighting broke out. The fighting included the use of warships and the capture of Yemeni fishermen. The motivation of Eritrea remained unclear. However, oil and gas discoveries were thought to be a factor. Yemen submitted the Hanish island problem to an international tribunal at the Hague in 1997. The following year, the international tribunal decided in Yemen's favor.
Tribal leaders in the Saudi Arabian-Yemini border area often contribute to violence and danger, disputing among themselves and with the Yemeni government. A U. S. consul noted in 1996 that air transport would reduce the risk to persons traveling outside the cities. It was also proposed that an armed escort be provided by a local tour company. A history of similar unrest clouds Yemeni relations with neighboring Oman along the eastern border.
Tribal leaders present a political and military challenge to peace in Yemen and may side with other Arab national interests, as they did in 1934. In addition, collecting booty is a tradition. During the civil war in 1994 the tribes seized heavy weapons, including artillery and armored vehicles. These weapons were turned against the Yemeni government in 1996 when troops tried to collect them.