Saddam sent a warning to Khomeini in mid-1988, threatening to launch a new and powerful full-scale invasion and attack Iranian cities with weapons of mass destruction. Shortly afterwards, Iraqi aircraft bombed the Iranian town of Oshnavieh with poison gas, immediately killing and wounding over 2,000 civilians. The fear of an all out chemical attack against Iran's largely unprotected civilian population weighed heavily on the Iranian leadership, and they realized that the international community had no intention of restraining Iraq. The lives of the civilian population of Iran were becoming very disrupted, with a third of the urban population evacuating major cities in fear of the seemingly imminent chemical war. Meanwhile, Iraqi conventional bombs and missiles continuously hit towns and cities, destroying vital civilian and military infrastructure, and increasing the death toll. Iran replied with missile and air attacks, but not sufficiently to deter the Iraqis.