Operation Gift, was an Israeli Special Forces operation at the Beirut International Airport in the evening of December 28, 1968, in retaliation for the attack on the Israeli Airliner El Al Flight 253 two days earlier by the Syria-based Popular Front for the Liberation of Palestine (PFLP).
The attack drew widespread international condemnation. The United Nations Security Council adopted Resolution 262 on 31 December 1968, which condemned Israel for the "premeditated military action in violation of its obligations under the Charter and the cease-fire resolutions", and issued a "solemn warning to Israel that if such acts were to be repeated, the Council would have to consider further steps to give effect to its decisions", and stated that Lebanon was entitled to appropriate redress. The resolution was adopted unanimously.
The raid resulted in a sharp rebuke from the United States, which stated that nothing suggested that the Lebanese authorities had anything to do with the El Al Flight 253 attack. The French recalled their ambassador.
Prior to this Lebanon’s Christian government had been a dissenting voice in the Arab league - seeing Israel as a potential Ally against Islamic domination. Despite absorbing tens of thousands of refugees by late 1947/early 1948 They sent no units or commander to participate in the 1948 war (only some volunteers went) likewise they sent zero ground troops in 1968 - only flying 2 recon aircraft (one of which was shot down). The events of Operation Gift seriously destabilized the Lebanese Christian government, led to the Lebanese Civil war and may have destroyed chances of an alliance.
https://en.m.wikipedia.org/wiki/1968_Israeli_raid_on_Beirut_Airport