Meanwhile, Israel grew concerned over the Syrian military presence in Lebanon, particularly as the Syrian Army pursued retreating Palestinians and Muslim leftists into southern Lebanon. Israel believed that the Syrian forces, massed in southern Lebanon, might attack Israel across the unfortified Lebanese border and thus avoid the need to penetrate the heavily defended Golan Heights. Therefore, Israel enunciated its "Red Line" policy, threatening to attack Syria if it crossed a line identified geographically with the Litani River (see fig. 3). Thus, Syrian forces were generally precluded from moving south of the Litani. The Red Line was a geographic line, but it was also more subjective than a line on a map. Israeli prime minister Yitzhak Rabin identified the Red Line as a guideline for gauging Syria's overall military behavior in Lebanon, and he described several criteria Israel would use: the objectives of Syrian forces and against whom they were operating, the geographical area and its proximity to Israel's borders, the strength and composition of Syrian forces, and the duration of their stay in a given area.
Data as of December 1987