Historians date the entry of Syrian regular troops to 1 June 1976 (Ménargues gives 9 June). President Assad announced it in the presence of the visiting Soviet Prime Minister Kosygin, citing appeals from the Akkar villages of Qubayat and Andaqit, besieged since January and attacked by the Lebanese Arab Army on 27 May. Columns moved towards Akkar and Tripoli, Zahleh and the Bekaa, and Sidon by way of Jezzine. Estimates of the force range from 6,000 men at the start (with 260 armoured vehicles, according to Ménargues) to 12,000-15,000 within weeks, with 250-300 tanks (de Clerck and Malsagne).

Counts of those evacuated between 21 August and 1 September differ: 14,398 Palestinians and Syrians, including 664 women and children of PLO cadres (de Clerck and Malsagne); 14,938 Palestinians by 30 August (Ménargues); about 15,000 by sea plus 6,500 Syrian and PLA soldiers by land (Hanf). On 1 September President Reagan announced his peace plan.

Massacres were committed on both sides: Druze fighters killed Christians at Bmaryam, Bhamdoun, Ma'asir al-Chouf and many other villages, and Lebanese Forces fighters killed Druze at Kfarmatta and in villages on their line of retreat. For September to December 1983 de Clerck and Malsagne give more than 1,500 Christians and 207 Druze massacred, 324 PSP and 368 Lebanese Forces fighters dead, and over 163,000 Christians driven from the region. Traboulsi gives 62 villages destroyed, Hanf about sixty.

Karami had announced his resignation on 4 May. Who was responsible is disputed: Hanf (1993) writes that it was never established who planted the bomb in the army helicopter; de Clerck and Malsagne report that it was attributed to Samir Geagea's Lebanese Forces, and Picard notes that Geagea was later tried for it. Selim al-Hoss, Minister of Education, became acting prime minister; the cabinet never met again and governed by circulated decrees.