According to the IDF, Hizbullah has fired more than 1,000 Katyusha rockets into northern Israel since the beginning of the most recent escalation of violence, killing 17 people, damaging roads and buildings, sending hundreds of thousands living in northern communities into bomb shelters, and shutting down the North's economy. Hizbullah and before it the PLO have fired these rockets from southern Lebanon since the 1950s, when Lebanon and Syria acquired the weapons from Soviet and Chinese stockpiles leftover from World War II. The Katyusha (little Katie in Russian) was initially a primitive projectile designed in the late 1930s by Swedish rocket engineer Georgy Langemak for the Red Army. It was first used in 1941, during the initial stages of the German invasion of the Soviet Union. The term Katyusha actually refers to several variants of unguided rockets based on the original Soviet design and produced over the past half-century. Much of Hizbullah's arsenal of Katyushas consists of older versions, including the 122 mm. model, with a range of 20 to 25 km., and the 107 mm. variation, with a range of 8 to 10 km. Due to their lack of size and onboard guidance systems, these individual Katyushas do not pose a great threat to infrastructure or buildings, although the fatalities are all-too tangible proof of their potential to kill. However, Hizbullah is known to have a number of truck-mounted multi-barrel rocket launchers capable of firing salvos of 40 rockets at a time. According to estimates by Israeli officials and military experts, Hizbullah had approximately 10,000 Katyusha rockets before the beginning of the current violence. The mobility of the multiple-rocket launchers makes them difficult for the IAF to pinpoint and destroy. The latest barrages of rockets against northern Israel have confirmed the longstanding concerns of Israeli military experts - that with the help of Iran and Syria, Hizbullah has also been able to acquire 240mm. versions of the standard 122mm. Katyusha, as well as the Iranian Fajr-3 rocket, a third-generation Katyusha with a range of 35-45 kilometers. Iranian Fajr-5 rockets have a 70-km. range. And variants of the Zelzal missile have ranges of 150-km. and even 200-km., bringing Tel Aviv well within potential range from Lebanon. These systems are, potentially, capable of being armed with conventional high explosives, chemical, biological and radiological dispersion warheads. Israeli intelligence is understood to have assessed that Hizbullah does not a non-conventional weapons capability. The Fajr-3 and Fajr-5 rockets are much less accurate than Iran's Fajr-3 and Fajr-5 missiles, which have onboard guidance systems. As a very general rule of thumb, Hizbullah's rockets are said to be accurate to only one percent for every kilometer traveled. In other words, a rocket fired from 40 kilometers would be accurate to approximately 400 meters.