The 1949 Armistice Agreements terminated open hostilities, set out demarcation lines and enabled exchange of prisoners of war. The initial hope was that they would lead to peace treaties but it took another thirty years before the first peace treaty, with Egypt, was signed. The institution of demilitarized zones proved to be problematic as it led to disagreements regarding sovereignty and civilian control of these areas. The Mixed Armistice Commissions often found themselves acting as legal arbitrators on difficult international legal issues for which the Chairman, a military officer seconded to the UN was not qualified. Armistice Demarcation Lines (ADL) are normally temporary, but the 1949 Armistice Demarcation line between Israel and the West Bank and Gaza has achieved a certain de facto status. Most States consider the ADL should serve as a basis for negotiating a future border between Israel and the Palestinians.