Nowhere To Hide - Killer drones that can see through walls.By William Saletan

What WIlliam Saletan describes here could be the secret weapon alluded to by Woodward. t

For the last couple of days, in the Human Nature blog, I've been looking into a breakthrough cryptically reported in Iraq and Afghanistan: the ability of U.S. unmanned aerial vehicles to identify and track human targets "even when they are inside buildings." Several recently reported technologies might account for it, but Slate reader fozzy suggests looking for the answer in a military research field called STTW, usually translated as "sense-through-the-wall." Has this ability been extended to a distance that allows it to be used by aerial drones?

Fozzy cites a March 2008 Army technical report on the latest progress in STTW radar methods. (Warning: Most of the documents I'm linking to here are PDFs, and some take a long time to open.) With a few more clicks, I pulled up an April 2008 report from the same research team. Both reports focus on "detecting and identifying humans enclosed in building structures." "Through-the-wall sensing is currently a topic of great interest to defense agencies both in the U.S. and abroad," says the April report. "The U.S. Army Research Laboratory (ARL) has been active in all these fields of investigation, approaching these issues both through hardware design and radar measurements and through computer simulation of various STTW scenarios."

Display from an unmanned aerial vehicle

Meanwhile, up in the air, drone designers have been struggling with a similar problem: seeing through "darkness, bad weather, and tree canopies." The crucial contribution drones have made in Iraq—providing instant, on-demand customized video to ground forces—doesn't work where the drones' cameras can't see. So American engineers are developing radar that penetrates outdoor obstacles.

What seems to be happening is that these two projects—STTW and UAVs—are converging. In other words, unmanned vehicles that can see through walls. In some planning documents, the merger is explicit. A 2006 "Operational Needs Statement" from the military's Joint Urban Operations Office calls for a "STTW sensor mountable on both manned and unmanned vehicles," including "UAV platforms." A Navy bulletin calls for the same thing.