After 400,000 Peace Now protesters rallied in Tel Aviv to demand an official government inquiry into the massacres, the official Israeli government investigation into the massacre at Sabra and Shatila, the Kahan Commission (1982), was conducted. The inquiry found that the Israeli Defense Forces were indirectly responsible for the massacre since IDF troops held the area. The commission determined that the killings were carried out by a Phalangist unit acting on its own, but its entry was known to Israel and approved by Sharon. Prime Minister Begin was also found responsible for not exercising greater involvement and awareness in the matter of introducing the Phalangists into the camps.