Top officials late of the CIA, Army, and Department Defense agree, according to a just-out non-partisan panel report: the United States' use of drones is dangerous, risking both war without end and a global drone arms race. Their public arguments parallel a largely unseen debate inside the US government over how to control the spread of unmanned combat vehicles around the world.

"The proliferation of military robotics ... is likely inevitable"

The views from these officials came from in a report published by the Stimson Center. But this isn't your average, boring think-tank white paper: it represents the consensus view of a task force made up largely of former high-level government officials. The task force's two chairs were Rosa Brooks, a former Counselor to the Undersecretary of Defense for Policy, and General John Abizaid, formerly the head of US Central Command.

The task force's argument, unlike a lot of the debate over drones, is pretty subtle. Their position isn't that drones are intrinsically unlawful or overly destructive. Rather, it's that drones create incentives for policy choices that could have devastating consequences.

Drones are really well-suited to targeting small clusters of targets. They can fly much longer than conventional planes, allowing them to follow targets until they've got a good shot. They fly low for precision targeting. And they don't put US pilots at risk.

The problem with all this, according to the report, is that these capabilities make it hard for US policymakers to resist constantly employing small-level drone strikes around the world:

While we do not believe that UAV strikes cause disproportionate civilian casualties or turn killing into a "video-game," we are concerned that the availability of lethal UAV technologies has enabled US policies that likely would not have been adopted in the absence of UAVs. In particular, UAVs have enabled the United States to engage in the cross-border use of lethal force against targeted individuals in an unprecedented and expanding way, raising significant strategic, legal and ethical questions.

If you've got what seems like a cost-free way to take out potential threats to the United States, why would you ever stop using it? And that way, the report warns, lies perpetual war.

The Stimson task force identifies a number of specific problems within the larger problem of a future of constant drone strikes. First, ease of drone strikes makes it easy to avoid thinking strategically about whether they're doing more harm than good. "To the best of our knowledge," the task force concludes "the US executive branch has yet to engage in a serious cost-benefit analysis of targeted UAV strikes as a routine counterterrorism tool."

"the US executive branch has yet to engage in a serious cost-benefit analysis of targeted UAV strikes"

This is hugely troubling, for a number of reasons the report raises. Do constant drone strikes help terrorist recruiting more than they degrade the groups? Do limited drone strikes risk escalating to wider wars? Can this kind of war meaningfully be regulated by Congress? The Stimson authors thinks there's real concern in each of these areas — and that the US government isn't paying enough attention.

There's also a problem with international precedent and drone proliferation. Dozens of countries already have or have indicated interest in armed drones. The more the US uses them to strike purported terrorists around the world, the more of a risk there is that other countries start mimicking this policy. And even if you think the US is targeting the right folks, the Stimson Report warns, other countries might not be so stringent.

There's an interesting, related debate going on inside the US government about this right now. There isn't a clear US government policy about exporting armed drones. As the US is the world leader in drone technology, significant US drone exports could make drone proliferation happen much faster. Under what circumstances, and to what countries, should they be sold?

"It is not clear where the White House will come out"

There is disagreement within the Obama administration about selling drone technology abroad.

"It is not clear where the White House will come out," Micah Zenko, a fellow at the Council on Foreign relations, tells me. "The nonproliferation folks, centered at [the State Department], do not support liberalized armed drone exports," he wrote over email. "On the other side are [Defense department] folks, and some State regional bureaus, who want to export this capacity to allies, like Turkey, and non-allies like Singapore, as part of 'building partnership capacity.'"

Zenko himself has expressed concern about drone proliferation, and argues that the US government should closely study the technology before considering large-scale sales. Others have more optimistic views.

"The proliferation of military robotics ... is likely inevitable," says Michael Horowitz, a political scientist at the University of Pennsylvania who studies military technology. "Much better for close allies and partners to get systems from the US and learn to use them responsibly than to build them themselves or buy them from other countries."

It's productive that the White House is putting this much effort into reviewing the risks of drone proliferation. But the Stimson report suggests that we should be worried that the Obama administration isn't thinking nearly so critically about how they use the machines they already have.