Washington’s Global Drone monopoly has secretly and not so secretly killed perhaps 5,000 people overseas in the past dozen years. But it took a drunken hobbyist’s 42-oz. (1.2 kg) drone crash-landing at the White House on Jan. 26 to make it clear to most Americans that unmanned aerial warfare is about to become a two-way street. That $500 drone is the shape of things to come both at home and from enemies overseas. The question is whether the U.S. can find the legal and technical means to mount a credible defense.
Only recently have computers and GPS satellites made cheap and precise drones possible. But a certified drone boom is now under way: in the coming decade, the rest of the world is expected to spend nearly 10 times as much as the U.S. does to develop and produce drones ranging in size from passenger pigeons to passenger jets. More than 50 nations are building close to a thousand models. “These things are a real danger right now,” says retired Air Force general John Jumper, who first armed the Predator seven months before 9/11. “If al-Qaeda or ISIS could get something into the U.S. and fly it to do mischief, they’d do it this afternoon.”
Drones already play a role in everything from agriculture to weather forecasting (and soon, if Amazon and Domino’s Pizza have their way, home delivery). But for every positive use, there’s a malevolent one, ranging from nosy neighbors to drug smugglers to terrorists.
The rules of the sky remain cloudy: the U.S. is still drafting regulations to merge unmanned aircraft safely into the nation’s skyways.
“We don’t really have any kind of regulatory structure at all for it,” President Obama told CNN after the Chinese-made DJI Phantom landed in his backyard. (The President and First Lady were in India at the time, although their two daughters were at home.) He has ordered the FAA and other U.S. agencies to draft rules to “make sure that these things aren’t dangerous and that they’re not violating people’s privacy.” But such flight rules would apply only to those willing to follow them.
When it comes to drones, the U.S. could reap what it has sown. Washington always justified its use of lethal drones after 9/11 as a self-defense tactic against terrorists who wanted to attack America. Better to hunt down the bad guys in their backyard, the logic went, than to wait for them to strike the U.S. again. By that logic, terrorists seeking further revenge will almost surely send the drones humming our way for the same reason. “U.S. legal justification for its use of drones relies on a ‘global war’ concept that treats the entire world as a battlefield,” an Army military-intelligence officer wrote in 2013. The policy, he concluded, is “myopic.”
That policy may be especially shortsighted given the lack of defenses against drones. Smaller drones are limited by range, payload and speed. Larger drones may be more lethal, but they’re also easier to spot with radar when flying high or with eyes and ears when they are flying low to elude radar.
The threat isn’t only military. Larger drones can ferry contraband, like one that crashed into a Mexican parking lot just south of San Diego on Jan. 20 with more than 6 lb. (2.7 kg) of methamphetamine aboard. They’ve also been discovered trying to ferry drugs into prisons.
Sensor networks are popping up around government buildings, including nuclear sites and jails, to warn guards of unscheduled deliveries. Electronic jammers that cut an operator’s control of a drone are also an option, but they are currently illegal, in part because they can disrupt cell phones, GPS devices and aircraft signals needed for safe flight.
Drones are increasingly shredding the perception of personal privacy as well. Small drones outfitted with GoPro cameras to create nifty aerial footage can easily become peeping drones harassing neighbors. Homeowners can try to guard their privacy by registering their addresses at NoFlyZone.org, or by using a $1,000 acoustic sensor that will alert them to a drone’s approach. “But we only detect them,” says Brian Hearing of DroneShield, an 18-month-old company that has installed such detectors at 200 sites around the world.
The U.S. government is so concerned about the home-grown drone threat that it held a closed-door session with industry experts 10 days before the South Lawn incident. Daniel Herbert, who runs a Delaware drone business, attended the session, which featured three small drones carrying fake bombs. The government, he said, had a grim message: “If these things end up in the wrong hands, they don’t have the tools to deal with them.”
The most dangerous drones may soon approach the size of small planes, like those flown by the U.S. military overseas. Not only can they fly farther, but they can also carry bigger–and consequently deadlier–payloads, ranging from bombs to missiles to weapons of mass destruction. “There’s nothing on the market right now that’s as sophisticated as a Predator,” says Jumper, the retired general. But that will change. “It’s not too much of a leap from where we are now,” he says, “to a stealthy cruise missile that you could launch from a flatbed truck and fly at a low altitude, making it extremely difficult to pick up on radar.”
Read next: How to Defend Against Drones
This appears in the February 23, 2015 issue of TIME.