By 1988, with massive equipment imports and reduced Iranian volunteers, Iraq was ready to launch major offensives against Iran. In February 1988, Saddam began the fifth and most deadly "war of the cities". Over the next two months, Iraq launched over 200 al-Hussein missiles at 37 Iranian cities. Saddam also threatened to use chemical weapons in his missiles, which caused 30% of Tehran's population to leave the city. Iran retaliated, launching at least 104 missiles against Iraq in 1988 and shelling Basra. This event was nicknamed the "Scud Duel" in the foreign media. In all, Iraq launched 520 Scuds and al-Husseins against Iran and Iran fired 177 in return. The Iranian attacks were too few in number to deter Iraq from launching their attacks. Iraq also increased their airstrikes against Kharg Island and Iranian oil tankers. With their tankers protected by U.S. warships, they could operate with virtual impunity. In addition, the West supplied Iraq's air force with laser-guided smart bombs, allowing them to attack economic targets while evading anti-aircraft defenses. These attacks began to have a major toll on the Iranian economy and morale and caused many casualties.