Most notably Islam, in its scripture, dictates that water-bodies may not be poisoned even during a battle and enemies must be allowed access to water. Military forces of the Yishuv and subsequently of the State of Israel had recourse to a biological warfare strategy, in violation of the Geneva Protocol of 1925 prohibiting the use of chemical and biological agents in conflicts, of poisoning the wells of Palestinian villages, and those used by Arab armies during both the 1948 Palestine war and the 1948 Arab–Israeli War. When two undercover operatives engaged in poisoning wells in Gaza were caught by Egyptian forces, Egypt complained to the United Nations in May 1948. In the late 20th century, accusations of well-poisoning were brought up against Serbs, most notoriously in relation to the poisoning of Kosovo Albanians. There have also been accusations of well-poisoning as a part of the Srebrenica massacre. In the 21st century, reports of well contamination by Israeli settlers in the West Bank have surfaced. Cases include a 2004 incident in which rotting chicken carcasses were found in a well at At-tuwani near Hebron, and in 2006, an incident occurred in the Palestinian village of Madama, Nablus, in which neighbouring Israeli settlers both "poisoned the village's only well and shot at aid workers who came to clean it." History of well poisoning as libel Medieval accusations against Jews Despite some vague understanding of how diseases could spread, the existence of viruses and bacteria was unknown in medieval times, and the outbreak of disease could not be scientifically explained. Any sudden deterioration of health was often blamed on poisoning. Europe was hit by several waves of Black Death (often identified as bubonic plague) throughout the late Middle Ages. Crowded cities were especially hard hit by the disease, with death tolls as high as 50% of the population. In their distress, emotionally distraught survivors searched desperately for an explanation. The city-dwelling Jews of the Middle Ages, living in walled-up, segregated ghetto districts, aroused suspicion. An outbreak of plague thus became the trigger for Black Death persecutions, with hundreds of Jews burned at the stake, or rounded up in synagogues and private houses that were then set aflame. With the decline of plague in Europe, these accusations lessened, but the term "well-poisoning" remains a loaded one that continues to crop up even today among anti-Semites around the world. Walter Laqueur writes in his book