Given the task definition and input, reply with output. In this task, you're given a question, along with a context passage which has extra information available on certain terms mentioned in it. Your job is to determine which sentence(s) from the passage can be used to search for further information needed to answer the question.

Question: How long had Hafez al-Assad been the President of Syria for by the year he sent troops into Lebanon to fight PLO forces? Passage:According to historians William Cleveland and Martin Bunton, Beirut became an international banking center because of its “laissez-faire economic system”. Business owners from Cairo, Damascus, and Baghdad moved to Beirut for economic opportunities. Despite Lebanon’s cultural liberalism and economic prosperity, sectarian tensions remained as citizens identified themselves through their sects. With Muslims calling for greater representation and with Cold War tensions, Lebanese leadership had to decide whether to ally with the West or with Egypt, Syria and its Arab history. Christians wanted to continue alliances with the West but Muslims were drawn to Nasser's pan-Arabism. Multiple factors including sectarian tensions and Palestinian refugee settlement in southern Lebanon contributed to the beginnings of the Lebanese Civil War. In 1976, Syrian President Hafez al-Assad sent troops into Lebanon to fight PLO forces on behalf of Christian militias. This led to escalated fighting until a cease-fire agreement later that year that allowed for the stationing of Syrian troops within Lebanon. The Syrian presence in Lebanon quickly changed sides; soon after they entered Lebanon they had flip-flopped and began to fight the Christian nationalists in Lebanon they allegedly entered the country to protect. The Kateab Party and the Lebanese Forces under Bachir Gemayel strongly resisted the Syrians in Lebanon. Following the Israeli invasion into Lebanon in 1982, new Lebanese President Amine Gemayel sought the support of Syrian troops to stabilize the region. Syria fought Israeli troops after the latter's invasion of Lebanon.


In 1976, Syrian President Hafez al-Assad sent troops into Lebanon to fight PLO forces on behalf of Christian militias