1980 Syria concentrates forces in central Lebanon's Bekaa (al-Biqa) Valley and later moves in Soviet-made surface-to-air (SAM-6) missiles. When the Phalangists (Christians) occupy the hills around Zahle near the strategic Beirut-Damascus highway, Syria launches a major offensive against them. Israeli jets attack the Syrians and also bomb areas of Beirut in retaliation for PLO rocket attacks from Lebanon into northern Israel.