Unmanned aerial systems (UAS, or drones) could be used by malicious actors to conduct unauthorized surveillance or to deliver hazardous payloads within the United States. But defending against such threats may violate the law as currently written.

“Some of the most promising technical countermeasures for detecting and mitigating UAS may be construed to be illegal under certain laws that were passed when UAS were unforeseen,” the Department of Defense said in its legislative proposals for the FY 2018 defense authorization act. “These laws include statutes governing electronic communications, access to protected computers, and interference with civil aircraft.”

DoD therefore asked Congress to enact legislation that would authorize development of drone countermeasures for domestic use without violating “many provisions” of existing law. See section 1602 of the DoD draft defense authorization act for FY 2018, submitted to Congress on May 25.

“Certain statutes are especially problematic” for defending against UAS threats, DoD said. Several sections of Title 18 of the US Code “might be construed to prohibit access to or interception of the telemetry, signaling information, or other communications of UAS.”

“Furthermore, any attempt to interfere with the flight of UAS that pose a threat” could violate the Aircraft Sabotage Act, which prohibits damage to or destruction of aircraft.

“The proposed legislation would generally allow research, testing, training on, and evaluating technical means for countering UAS,” including monitoring, tracking, re-directing, disabling or destroying such aircraft.

A broader look at Countering Air and Missile Threats was recently published by the Joint Chiefs of Staff (Joint Publication 3-01, April 21, 2017).

Having developed and utilized unmanned aerial systems (UAS, or drones) for surveillance, targeting and attack, the US military now finds itself in the position of having to defend against the same technology.

The US Army last week issued a new manual on Counter-Unmanned Aircraft System Techniques (ATP 3-01.81, April 13, 2017).

“UASs have advanced technologically and proliferated exponentially over the past decade,” the manual notes. “As technology has progressed, both reconnaissance and attack capabilities have matured to the point where UASs represent a significant threat to Army, joint, and multinational partner operations from both state and non-state actors.”

The unclassified Army document describes the nature of the threat and then considers the options that are available for dealing with it. These range from various forms of attack avoidance (“Operate at night or during limited visibility”) to active defense, such as surface-to-air weapons.

“Defending against UAS is a difficult task and no single solution exists to defeat all categories of the… threat,” the manual says.

Last week, the Islamic State released video footage of one of its drones dropping a bomb on an Iraqi target, Newsweek reported.

Enemy use of unmanned aerial systems (UAS) is a growing threat to U.S. forces because of their low cost, versatility, and ease of use, according to a recent U.S. Army doctrinal publication.

“The UAS is the most challenging and prevalent threat platform to combined arms forces and therefore, a logical choice for enemy use.”

See Techniques for Combined Arms for Air Defense, Army Techniques Publication (ATP) 3-01.8, July 29, 2016.

As is the case with U.S.-operated drones, enemy UAS can be used to perform a range of functions from battlefield surveillance and targeting to precision strike, the Army document said. “The enemy will use UAS to fulfill multiple attack roles.”

The drone may deliver a weapon or be used as a weapon itself. “As an indirect attack platform, the UAS has the ability to carry the improvised explosive device or become the improvised explosive device.”

“Perhaps the most dangerous COA [course of action]… is the Swarm” in which “clusters of UAS” are used by an adversary simultaneously for surveillance, indirect attack and direct attack.

What to do about this? The answer is not fully articulated in the Army manual.

“Proper planning by leaders will ensure that units employ adequate force protection measures to counter the UAS threat. Units must develop tactics, techniques and procedures to counter this threat in their respective areas of operation.”

Simply destroying the enemy drone is not necessarily the right move, the manual said.

“Defeat does not equate [to] kinetic means; however, it is an option. Other defeat solutions could be limiting a surveillance threat from gaining information or following the air path of the UAS to the operator.”

Islamic State forces have used drones bearing explosive devices, the New York Times reported this month. See “Pentagon Confronts a New Threat From ISIS: Exploding Drones” by Michael S. Schmidt and Eric Schmitt, October 11.

Just last week, the U.S. Air Force detected and destroyed a drone “in the vicinity” of U.S. forces, Air Force Secretary Deborah Lee James said yesterday. See “Air Force: Small, weaponized drones a growing combat problem” by Jacqueline Klimas, Washington Examiner, October 24.

Before the Department of Defense can use an unmanned aerial system within the United States for domestic operations such as search and rescue missions or disaster response, specific authorization from the Secretary of Defense is necessary.

However, if DoD wants to use a UAS to help control domestic civil disturbances (such as a riot or insurrection), then further authorization from the President of the United State is required.

The patchwork of legal authorities and requirements for domestic military missions is presented in a newly updated DoD manual on Defense Support of Civil Authorities (DSCA).

Military support to civil authorities may be prompted by a variety of natural disasters and emergencies, including wildfires, earthquakes, floods, chemical, biological, radiological, and nuclear accidents or attacks, and — a new addition — cyber incidents. But such domestic missions have their own peculiar characteristics.

“Operations conducted by the US military in the homeland and US territories are very different from operations conducted overseas,” the DoD manual says, particularly since they are executed “under the authority and within the limitations of federal, state, and local laws.”

In particular, “For fear of military encroachment on civil authority and domestic governance, the PCA [Posse Comitatus Act] and policy limit DOD support to LEA [Law Enforcement Agencies],” the manual says.

More specifically, “DOD directives prohibit interdicting vehicles, searches and seizures, arrest, and similar activities (e.g., apprehension, stop, and frisk). Furthermore, engaging in questioning potential witnesses; using force or threats to do so, except in self-defense or defense of others; collecting evidence; forensic testing; and surveillance or pursuit of individuals or vehicles is prohibited.”

On the other hand, “the Insurrection Act permits the POTUS [President of the United States] to use armed forces under a limited set of specific circumstances and subject to certain limitations.”

(The President has used the authority under the Insurrection Act twice in recent history. In September 1989 the President ordered federal troops to the US Virgin Islands to restore order in the aftermath of Hurricane Hugo. In April 1992 the President ordered federal troops to restore order in Los Angeles during riots following the Rodney King verdict.)

The updated manual includes a new appendix presenting a matrix of domestic military missions along with the relevant approval authority and policy guidance.

For the first time, the manual includes “cyberspace-related incidents” among the circumstances that may trigger military involvement in domestic matters.

“Large-scale cyber incidents may overwhelm government and private-sector resources by disrupting the internet and taxing critical infrastructure information systems. Complications from disruptions of this magnitude may threaten lives, property, the economy, and national security…. State and local networks operating in a disrupted or degraded environment may require DOD assistance.”

See Multi-Service Tactics, Techniques, and Procedures for Defense Support of Civil Authorities (DSCA), Army, Marine Corps, Navy, Air Force, September 2015.

The authorized use of DoD unmanned aerial systems in domestic operations is described in Guidance for the Domestic Use of Unmanned Aircraft Systems, Policy Memorandum 15-002, February 17, 2015.