Let’s imagine the worst-case scenario involving domestic drones. No, not the tiny quadcopter whose operator mistakenly crashed it on the south lawn of the White House. Let’s try something scarier.

Take several drones, and equip each with a few pounds of explosives, shrapnel and ball bearings. Then send them on a one-way kamikaze mission. As the technology advances, network the drones so they travel in a group and explode at the same time.

The question is: How do you stop them?

It might sound farfetched. But scenarios like this are now worrying officials in the Pentagon and the Department of Homeland Security. A drone attack by evildoers hasn’t happened — yet. But it’s possible. German police arrested several far-right extremists who allegedly planned attacks with a drone in 2013.

Like the car bomb, the drone bomb could become a cheap, ubiquitous and anonymous way to deliver explosives. The machines can hop over fences, bypass checkpoints and move too fast for a security team to react to. What if the target is a congressman, general or a president?

The good news is that drones are easily jammed. Almost all rely on a radio link to a ground controller, which makes them vulnerable to electronic interference. With an accurate enough sensor, anyone can search and pinpoint drones nearby, tune their jammer to the same frequency and overwhelm the vehicle with electronic “noise.”

Most domestic drones are highly vulnerable to this attack. The average consumer drones available in a hobby shop typically communicate using a frequency of 2.4 or 5.8 gigahertz, or some combination of both if they carry wireless video cameras.

Two devices using the same frequency can conflict with each other, which makes flying drones in congested urban areas inherently risky. Wireless Internet routers inside cellphones and laptops often broadcast using the same frequencies.

Most drone software is also rarely encrypted. For years, even the military’s most advanced surveillance drones suffered from this vulnerability, which the Taliban used to intercept Predator drone surveillance videos over Afghanistan. In 2011, Iran used a more sophisticated form of GPS “spoofing” to capture a secretive RQ-170 drone operated by the Central Intelligence Agency.

There’s not much sympathy for the machines. The American public largely hates domestic use of drones, and only 3 percent are “very likely” to buy one this year, according to a recent Reuters American Insights poll.

But in a crowded area like a city or airport, searching and blocking — or hijacking — drones comes with its own set of problems. Sophisticated sensor and jamming devices are extremely expensive. A Homeland Security sensor deployed to spot — but not interfere with — drones flying above the Major League Baseball All-Star Game in Minneapolis last July “cost several hundred thousand dollars to operate for just that night,” reported the New York Times.

The Secret Service uses covert radio-frequency jammers inside a Chevrolet Suburban that travels with the president’s motorcade. These devices disable remotely triggered improvised bombs. But because they have to disable explosives set off by a potentially large number of frequencies, the jammers saturate a wide spectrum, occasionally interfering with cellphones nearby.

This is just a temporary inconvenience for anyone standing near the convoy. If you think that’s bad, a permanent electromagnetic shield around the White House would interfere with the whole neighborhood.

Jamming transmitters is also illegal under the Communications Act of 1934. But as journalist Marc Ambinder pointed out, the Secret Service has some wiggle room around this law.

It goes without saying that shooting a civilian drone out of the sky poses a whole other set of complications. But it’s happened outside the United States.

In December 2013, the shotgun-toting crew of a Chinese military helicopter shot down a fixed-wing drone, which looks like a tiny airplane, with an 8.5-foot wingspan, as it neared Beijing Capital Airport. The drone delayed several flights. According to the state-run People’s Liberation Army Daily, police soon arrested three employees of the private drone company Beijing UAV Sci-Tech and charged them with endangering public security.

The drone crash near the White House on Jan. 26 didn’t come close to posing a threat. The operator was merely a drunk employee of the National Geospatial-Intelligence Agency. So it’s unlikely the Secret Service will begin hovering above the nation’s capital on the lookout for unmanned vehicles — shotguns in hand.

Some would like the government to go further. After the drone incident at the White House, Representative Elijah Cummings (D-Md.) called for building a defense system akin to Israel’s Iron Dome.

Iron Dome uses guided missiles to intercept incoming rockets. “Just like our friends in Israel feel comfortable with that Iron Dome,” Cummings told the Washington Post, “I want the people in the White House to feel comfortable, too, and I want the people who are trying to do us harm to know they cannot penetrate that sky over the White House.”

But Iron Dome has a somewhat mixed success record, at best. Even if the interceptors hit a rocket, the incoming warheads, in many cases, continue tumbling down toward populated areas. The same is true for a drone. Then you have to worry about accidentally shooting whatever’s behind it. It could be a tourist or a commercial airliner.

Instead of a one-size-fits-all solution, it’s better to have a mix of systems. For the recreational pilot who loses control of his machine, better firmware can keep it from hovering over prohibited areas like the White House. Sense-and-avoid radars can instruct pilots on what to avoid. None of this will stop a dedicated bad guy, but it’s enough to cut down on errant robots flying off course.

Let’s leave the jamming for the worst-case scenarios.