●The Syrian army enters officially

On 1 June 1976 the Syrian army entered Lebanon officially with some 12,000 troops and hundreds of tanks, after months of indirect intervention through the Palestine Liberation Army and al-Saiqa and a failed mediation between the parties. The entry came at the request of President Suleiman Frangieh and the Lebanese Front, to halt the advance of the National Movement and the PLO, which then held about two thirds of the country, and to prevent the partition of Lebanon or its fall to a leftist–Palestinian alliance that Damascus saw as a threat to its interests. The forces advanced on two axes: from Masnaa into the Bekaa and along the Beirut–Damascus road as far as Sofar and Bhamdoun, and from the north through Akkar towards Tripoli, meeting resistance from the joint forces at Sidon and in the mountains. Egypt, Iraq and the PLO condemned the intervention; the Arab League met on 9 June and decided on a symbolic Arab security force that changed nothing on the ground. The entry opened the way to the siege of Tel al-Zaatar and its fall in August, and the Riyadh summit in October then legitimised the Syrian presence under the name of the Arab Deterrent Force.