Lebanese Army soldiers into the areas that the UN forces were stationed in Southern Lebanon. This was followed by an increase of IDF activity in Lebanon which culminated in a crisis over the positioning Syrian antiaircraft missiles. Operations included a nighttime commando raid on five Palestinian targets in Southern Lebanon, 9-10 April; the shooting down of two Syrian Army helicopters in the Beqaa valley, 28 April; a commando raid near Damour in which four Libyan and two Syrian soldiers were killed, 27 May. On 3 June 1982, Abu Nidal's militant group gravely wounded Israel's ambassador in London, Shlomo Argov, in an assassination attempt. In response, the Israeli Air Force bombed Palestinian refugee camps in Lebanon. The Palestinian militants shelled Israel's northern settlements in retaliation and resulted in the Israeli government's 4 June order to begin the 1982 Lebanon War. The operation was launched on 6 June and soon became a full-scale invasion. The Israeli plan was to drive the PLO away from the Israeli border and help Bachir Gemayel's Phalangist militia take control of south Lebanon. During the war, the IDF faced the Syrian military, Palestinian militants and various militias. The IDF engaged in urban warfare and shelled Beirut to hit PLO headquarters. The IDF achieved some impressive military results – such as wiping out the entire Syrian air defense system in the first days of the war, under the command of IAF Major general David Ivri. But it also had some failures, such as the Battle of Sultan Yacoub. The operation was designed to be limited – both in time and area – but the IDF advanced far beyond the planned "40 kilometers" under the command of Defense Minister Ariel Sharon. The mounting Israeli casualties in Lebanon, combined with the Sabra and Shatila massacre, resulted in mass protests by the Israeli public against the war – which resulted in a cease-fire agreements and the establishment of the Kahan Commission to investigate the massacre. Kahan Commission In concluding that Eitan was "in breach of duty that was incumbent on the Chief of Staff" the Commission focused on two points: Firstly, that he did not take into consideration the "danger of acts of vengeance and bloodshed" when he, with the Minister of Defence, decided to send the Phalangist militia into the refugee camps. The commission argued that it was "common knowledge ... that there was a possibility of harm to the