In April 1980 the presence of UNIFIL soldiers in the buffer zone led to the At Tiri incident. On 17 July 1981, Israeli aircraft bombed multi-story apartment buildings in Beirut that contained offices of PLO associated groups. The Lebanese delegate to the United Nations Security Council claimed that 300 civilians had been killed and 800 wounded. The bombing led to worldwide condemnation, and a temporary embargo on the export of U.S. aircraft to Israel.