At the end of October, the Pentagon put out a request for information, or RFI, for new technologies “countering” commercial drones that are armed with chemical, biological, or massively destructive weapons. Specifically, the request asks for ideas on “emerging technologies, technical applications and their potential to counter a low-cost, small/man portable, commercial off-the-shelf unmanned aerial system (UAS) carrying a chemical and/or biological WMD payload.” And that includes “electronic systems that can interdict defeat or deny hostile use of UAS” and “systems providing the capability to intercept and neutralize the UAS. Both kinetic and non-kinetic solutions are encouraged and should cover both” the United States and global applications. The project, called Thunderstorm, will feature a technology demonstration in the second fiscal quarter of 2015 at Mississippi’s Camp Shelby.

The first portion of the request asks for ideas on technology to outfit drones with chemical weapons detectors. It’s another area of intelligence, reconnaissance and surveillance where flying robots that don’t sleep or blink or breathe could easily outperform humans. The biggest technological hurdle here is simply shrinking the sensors to the point where they can fit on relatively small drone but still be robust enough to pickup the most popular poisons.

The RFI is looking for the drone to be able to detect a wide variety of nerve agents like Sarin as well as industrial compound toxins and even flowers and wildlife, or “persistent and natural flora (providing biological surveillance on current and emerging flora).” It should be able to reach an altitude of 1000 feet, fly for at least 30 minutes without recharging and be able to actually collect samples and fly them back to defense department labs for analysis.

It’s the second portion of the RFI that speaks to a fast growing military worry: how to down the thousands of potentially dirty drones that could be swarming toward the United States in the decade ahead.

As many as 30,000 unmanned aerial vehicles will be darkening America’s skies by 2020, according Todd Humphreys of the University of Texas at Austin. They could be engineered to carry dangerous payloads or simply used as weapons. It’s an area that has attracted increasing Pentagon focus. A December 2012 meeting at Oklahoma’s Fort Sill, for instance, brought 120 representatives together from the services to discuss methodologies for countering UAVs with talks and discussions scheduled to continue. Around the same time, the Naval Postgraduate School disclosed the existence of a classified research effort called Project Jason to “characterize and understand the threats posed by swarms of UAV,” according to the school’s website.

In a request for proposals from February, the military asked for ideas on counter UAV technologies to detect drones that were both large and even “micro-sized.”

(Related: Every Country Will Have Armed Drones Within 10 Years)

Some of the capabilities featured in the most recent request include “sensors, software, or computers to detect and classify Command, Control, Communications, Computers, Collaboration and Intelligence (C5I) and sensor systems that facilitate rapid detection, identification and classification of UAS targets.”

As many as 30,000 unmanned aerial vehicles will be darkening America’s skies by 2020.

How easy is it to detect drones? Simple enough that you can do it at home, in some cases.

A company called Domestic Drone Countermeasures will sell you a kit consisting of “three boxes: a Primary Command and Control Module and two Detection Sensor Nodes. These three boxes create a mesh network that can triangulate moving transmitters.” You can increase the size the mesh network to detect the drone radio signals over a wider area, up to 200 feet. (Droneshield.org is also worth checking out.)

But detecting the presence of a drone is different from tracking a drone’s location, movement, or classifying its type or payload.

Achieving that level of detection capability requires more advanced radar equipment that military is looking to shrink down and make more mobile. Last September, the Air Force modified the Joint Surveillance Target Attack Radar System aboard one of its JSTARS test jets to perform a massive counter-UAV exercise. JSTARS is “an airborne system designed to find and track ground and maritime targets, as well as slow-moving fixed-wing aircraft and rotating antennas.”

Here’s how they described the test. “Once JSTARS…called ‘on-station,’ UAVs launched from the naval air station in intervals and flew patterns over water. The crew tested the new capabilities of the radar by attempting to detect and track the UAVs…They did not have advanced knowledge of the take-off times or patterns of flight of the target aircraft.”

Drone detection and tracking on the ground comes in various forms. One of the more interesting is a radar truck called Green Rock, developed by Israeli defense contractor Israel Aerospace Industries. The Green Rock tracks low-flying UAVs as well as rockets and mortars via Phased-Array Pulse Doppler Radar.

If you can detect the identity of the drone and find it, how do you get it down?

Today, the primary drone counter measure for disrupting drones is communication and radar jamming, hurting the ability of the drone to communicate with its operator. The military is paying Raytheon $10 billion to build what the military is calling the Next Generation Jammer.

If detection tech can be made small and cheap enough, the ultimate weapon against swarms of cheap drones will likely be… swarms of cheap drones.

But future counter-drone technologies include the various direct energy weapons making their way onto trucks and planes and particularly ships and boats. The Office of Naval Research, ONR, has made this a particular focus.

"We can expect that our adversaries will increasingly use UAVs and our expeditionary forces must deal with that rising threat," Col. William Zamagni, said in a June press release announcing ONR’s award in the Ground-Based Air Defense Directed Energy On-the-Move program, GBAD, program.

If detection tech can be made small and cheap enough, the ultimate weapon against swarms of cheap drones will likely be… swarms of cheap drones. It’s a research project underway at the Naval Postgraduate School, where in 2012 professor Timothy Chung said he was looking to put together a massive swarm on swarm drone challenge. This effort was to culminate in two teams, each with 50 Harpy style small drones “Duk[ing] it out over the skies of Camp Roberts,” in California in 2015.

In the meantime, ideas for the Thunderstorm project are due in on Nov. 26.