On March 15 1978, the Lebanese Government submitted a strong protest to the United Nations Security Council against the Israeli invasion, stating that it had no connection with the Palestinian operation. On March 19, 1978 the Council adopted resolution 425, in which it called upon Israel immediately to cease its military action and withdraw its forces from all Lebanese territory. It also decided on the immediate establishment of the United Nations Interim Force in Lebanon (UNIFIL). The first UNIFIL troops arrived in the area on March 23 1978.
On October 7, 2000, three Israeli soldiers, Adi Avitan 22, Staff Sgt. Benyamin Avraham 21, and Staff Sgt. Omar Sawaidwere 27 were abducted by the Hezbollah resistance organization. They were abducted while patrolling the southern (Israeli) side of the Israeli-Lebanese border. This borderline is officially recognized by the UN Secretary General and the Security Council as the Israeli deployment line, and is fully in accord with Security Council Resolution 425. The soldiers were killed either during the attack or in its immediate aftermath .
The Blue Line is based on the deployment of the IDF prior to March 14 1978. It should not be confused with the Green Line, established in 1949, which is the armistice line of the 1948 Arab-Israeli War. The 1949 line is in turn the same as the 1923 Mandate Line which was the border between France and Britain's territory (see: Treaty of Sèvres); Lebanon is an ex-French mandate and Israel an ex-British mandate. (See League of Nations). The 1949 agreement stated that the line would follow the 1923 line. In 1923 38 boundary markers were placed along the 49 mile boundary and a detailed text description was published. The 2000 Blue Line differs in about a half dozen short stretches from the 1949 line, though never by more than 475 meters.
Borders are usually negotiated between countries, and between 1950 and 1967 Israeli and Lebanese surveyors managed to complete 25 non-contiguous kilometers and mark (but not sign) another quarter of the international border. In April 17 2000, when Israeli Prime Minister Ehud Barak announced that Israel would begin withdrawing its forces from Lebanon, the Lebanese government did not want to take part in marking the border. The UN thus conducted its own survey based on the line discussed in UN Security Council Resolution 425.
From May 24 to June 7 2000, the UN Special Envoy travelled to Israel, Lebanon and the Syria to follow up on the implementation of the Secretary-General's May 22 report. The United Nations cartographer and his team, assisted by UNIFIL, worked on the ground to identify a line to be adopted for the practical purposes of confirming the Israeli withdrawal. While it was agreed that this would not be a formal border demarcation, the aim was to identify a line on the ground closely conforming to the internationally recognized boundaries of Lebanon, based on the best available cartographic and other documentary evidence.
On June 7 the completed map showing the withdrawal line was formally transmitted by the Force Commander of UNIFIL to his Lebanese and Israeli counterparts. Notwithstanding their reservations about the line, the Governments of Israel and Lebanon confirmed that identifying this line was solely the responsibility of the United Nations and that they would respect the line as identified. On June 8, UNIFIL teams commenced the work of verifying the Israeli withdrawal behind the line.
On June 16, the Secretary-General reported to the Security Council that Israel had withdrawn its forces from Lebanon in accordance with resolution 425 (1978) and met the requirements defined in his report of May 22 2000; namely, Israel had completed the withdrawal in conformity with the line identified by the United Nations, South Lebanese Army militia had been dismantled, and all detainees held at Al-Khiam prison had been freed.
The withdrawal line has been termed the Blue Line in all official UN communications since.