There's big concern about those small devices in the U.S. intelligence community.
So when a man said he was flying a drone for fun just after 3 a.m. in downtown Washington, D.C., and had an accidental crash-landing into a tree on the wrong side of one of the world's most highly protected fences, he didn't merely touch the famous property at 1600 Pennsylvania Ave.
He also touched a nerve.
In interviews, U.S. military officials have expressed fear that the cheap, increasingly popular recreational items sold at electronics stores could be used as terrorist weapons.
"It's a very insidious threat," one high-ranking U.S. military officer told The Canadian Press in a recent interview. "If we don't take that very seriously, it could be dangerous...
"We have to get our brains around that."
One concern he specifically mentioned was terrorists targeting a VIP. With a few modifications, he said, a $300 gadget used for aerial photography could be transformed into an airborne improvised explosive device.
The military has dedicated numerous conferences to the topic in recent years. There's also a growing body of academic research. A study at the University of Birmingham in the U.K. last year warned drones could be used for:
—Illicit reconnaissance missions. In one example late last year, French authorities reported that most of the country's 19 nuclear facilities had experienced drone flyovers in restricted airspace over a brief period, in flights that occurred mainly overnight and appeared to have been part of a co-ordinated effort.
—Explosions. The Birmingham study said a small-scale blast from a toy drone could kill people, or be used to prevent authorities from responding to a scene.
—Chemical attacks on crowds, for instance at a sporting event.
Norad, the Canada-U.S. agency that's been monitoring the skies for aerial threats since the Cold War, now says it's developing a policy to deal with small unmanned aerial vehicles, in conjunction with U.S. law enforcement and the U.S. Federal Aviation Administration, which has spent years working on commercial regulations for drones.
Norad is already testing blimps over Washington to detect more traditional threats like cruise missiles, and also more modern ones like drones.
"They are becoming more and more ubiquitous," one Norad official said recently. "If I'm a bad guy I can go pick one up at the local toy shop and fit them with explosives or chemicals."
He said terrorists are changing their tactics, and policy-makers have to evolve too.
But one officer at Norad said there are, fortunately, limits to drones' illicit potential. Their size alone, he said, reduces the potential damage one might cause.
The one that crashed Monday into the White House property was a two-foot device with four propellers.
"Most drones are small and they don't carry a lot of payload," U.S. Army Col. Steve Sicinski said during a tour of the Norad facility last summer.
"A drone, in and of itself, does not make a good weapon."
A Canadian military official concurred.
He said commercially available drones are designed to carry cameras — not big payloads. So the explosions one might produce would be much smaller than the ones from a military drone, he said.
It's also fairly easy to jam their signals, the official added.
No date has yet been set for the release of the commercial drone regulations in the U.S. The Federal Aviation Administration mostly bans commercial drone flights like those Amazon.com has famously announced it wants to test. Recreational users are barred from flying drones higher than 122 metres, or within eight kilometres of an airport.
The Secret Service hasn't said whether charges will be laid in the latest incident.