( AP )- Palestinians say they know when an Israeli drone is in the air: Cell phones stop working, TV reception falters and they can hear a distant buzzing. They also know what's likely to come next - a devastating explosion on the ground.
Palestinians say Israel's pilotless planes have been a major weapon in its latest offensive in Gaza, which has killed nearly 120 people since last week.
"Our experience is that the drone missile is successful in hitting its targets, and it's deadly," said Dr. Mahmoud Assali, a Palestinian physician who works in the emergency room of a northern Gaza Strip hospital that has often treated Palestinian gunmen hit by Israeli drones.
"The drone has a zone of around 15 meters (50 feet) where it decimates everything. It targets people and leaves them in pieces," Assali said.
Israel is at the forefront of the drone technology that is increasingly being used in hotspots around the world. The unmanned craft provide a deadly and cost-effective alternative for armies to target enemies, without risking their own pilots' lives and reducing civilian casualties in heavily populated areas.
The unmanned craft are guided by remote control from the ground. Because of their small size and relatively low speed, their low-yield missiles can be aimed precisely.
The use of drones is shrouded in secrecy, and Israeli defense officials refuse to comment publicly on whether they are being used in airstrikes in Gaza. However, Israeli officers in private conversations have confirmed use of the weapons.
Wary Gaza militants using binoculars are on constant lookout for drones. When one is sighted overhead, the militants report via walkie-talkie to their comrades, warning them to turn off their cell phones and remove the batteries for fear the Israeli technology will trace their whereabouts.
A militant from the southern Gaza Strip who belongs to the Islamic Jihad group said drones were mostly used to target individuals, and not structures. He said they often hovered at much higher altitudes than manned aircraft and their missiles were frequently more destructive, leaving deep gashes where they landed.
The militant said the drones usually targeted slow-moving targets, like people walking, or cars slowing down to avoid potholes in a road.
"It looks like it makes small circles in the sky, but before it's about to fire a missile, it slows down," the militant said, speaking on condition of anonymity because he feared being identified by Israel. "It's not like any other plane. You don't see the missile leaving, it's very quiet."
Damian Kemp, an aviation desk editor at Jane's Defence Weekly, said Israel is probably the first country in the world to use unmanned aerial vehicles, or UAVs, for both surveillance and to fire missiles. Israel is a world leader in the field and "capable of doing everything from the very small to the very large," he said.
He said drones were likely more accurate, cost-effective and safer than manned F-16 fighter jets and Apache helicopters.
"The key thing in a UAV is it does missions that are dull, dirty and dangerous," Kemp said. "They can be up there for a long time and in areas where you don't need to put a pilot at risk."
Jaber Wishah, deputy director of the Palestinian Center for Human Rights, said his group has received reports about drones firing missiles for more than three years.
"The kind of missile - from the shrapnel we've gathered - appears to be small," Wishah said. "But do we have documentation, photographs of a drone? We don't."
Israel has long been considered the world leader in drone technology and proudly exhibits its products at international air shows. But it maintains its drones are for surveillance purposes, and refuses to confirm using them in airstrikes.
Doron Suslik, a top official at the Israel Aerospace Industries, which manufactures drones, said the company has customers from all over the world, including Switzerland, France and India, with annual sales of $500 million to $600 million.
He refused to divulge the drone's military capabilities, citing his clients' desire for confidentiality. Government and army officials also refused to comment on the drone's firing capabilities.
Israel has used unmanned aircraft since the early 1970s, and its fleet has steadily increased. Air force officials say drones have become such an integral part of Israel's air power that their flight hours now outnumber those of manned fighter planes.
Last March, Israel unveiled its largest unmanned aircraft to date at a seaside air force base in central Israel. The Heron, with a 54-foot wingspan, can fly for up to 30 hours at a speed of 140 mph and a height of 30,000 feet.
Kemp of Jane's Defence Weekly, said a newer version, the Heron TP, was unveiled in June in Paris. With a wingspan of 85 feet, it can fly for as long as 36 hours and carry a maximum payload of 2,200 pounds.
The U.S. Army has used drones such as the MQ-1 Predator and the MQ-9 Reaper for airstrikes against al-Qaida commanders and other militants in Afghanistan and Iraq. U.S. drones have also reportedly killed militants in Pakistan and Yemen.
U.S.-made Predators are a common sight in the skies of Baghdad, equipped with cameras, sensors and radar that can capture video and still images.
The U.S. Air Force operates a fleet of roughly 100 Predators. The CIA also uses the aircraft and was closely involved in its development. It provides almost real-time, full-motion video and is remotely piloted - Air Force pilots control and operate the aircraft in Iraq and Afghanistan from Creech Air Force Base near Las Vegas.
The Reaper is four times heavier than the Predator, can fly twice as fast and twice as high.
In January, a missile fired from a Predator killed Abu Laith al-Libi, a top al-Qaida commander, in Pakistan's lawless tribal region of north Waziristan. Coalition forces in Afghanistan are believed to have launched a number of missile strikes from drones against Taliban and al-Qaida militants hiding on the Pakistani side of the border, but the U.S. military has never confirmed them.