On October 15, 2015, a Russian passenger airliner, Metrojet Flight 9268, was downed by a bomb over the Sinai Peninsula in Egypt, killing all 224 people aboard. The bomb, placed aboard the plane by ISIS affiliates, caused the aircraft to crash, shortly after taking off from Sharm el-Sheikh. The tragedy highlighted the ongoing threat of terrorism in the region and prompted tighter security measures for international flights. The incident was one of the deadliest terrorist attacks involving a civilian airplane in recent history. In response, Russia intensified its airstrike campaign in Syria, where ISIS had a presence.