Do any nations have fully autonomous weapons that operate with no human supervision? Generally speaking, fully autonomous weapons are not in wide use, but there are a few select systems that cross the line. These weapons can search for, decide to engage, and engage targets on their own and no human can intervene. Loitering munitions are one example.
Loitering munitions can circle overhead for extended periods of time, searching for potential targets over a wide area and, once they find one, destroy it. Unlike homing munitions, loitering munitions do not require precise intelligence on enemy targets before launch. Thus, a loitering munition is a complete “weapon system” all on its own. A human can launch a loitering munition into a “box” to search for enemy targets without knowledge of any specific targets beforehand. Some loitering munitions keep humans in the loop via a radio connection to approve targets before engagement, making them semiautonomous weapon systems. Some, however, are fully autonomous.
Fully Autonomous Weapon System (human out of the loop)
The Israeli Harpy is one such weapon. No human approves the specific target before engagement. The Harpy has been sold to several countries—
Chile, China, India, South Korea, and Turkey—and the Chinese are reported to have reverse engineered their own variant.
HARM vs. Harpy
Type of
weapon Target Time to
search Distance Degree of autonomy
HARM Homing
missile
Radars Approx.
4.5 minutes
90+ km Semiautonomous weapon
Harpy Loitering munition
Radars 2.5 hours 500 km Fully
autonomous weapon
The difference between a fully autonomous loitering munition and a semiautonomous homing munition can be illustrated by comparing the Harpy with the High-speed Anti-Radiation Missile (HARM). Both go after the same type of target (enemy radars), but their freedom to search for targets is massively different. The semiautonomous HARM has a range of
90-plus kilometers and a top speed of over 1,200 kilometers per hour, so it is only airborne for approximately four and a half minutes. Because it cannot loiter, the HARM has to be launched at a specific enemy radar in order to be useful. The Harpy can stay aloft for over two and a half hours covering up to 500 kilometers of ground. This allows the Harpy to operate independently of a broader battle network that gives the human targeting information before launch. The human launching the Harpy decides to destroy any enemy radars within a general area in space and time, but the Harpy itself chooses the specific radar it destroys.
Semiautonomous vs. Fully Autonomous Weapons For semiautonomous weapons, the human operator launches the weapon at a specific known target or group of targets. The human chooses the target and the weapon carries out the attack. Fully autonomous weapons can search for and find targets over a wide area, allowing human operators to launch them without knowledge of specific targets in advance. The human decides to launch the fully autonomous weapon, but the weapon itself chooses the specific target to attack.
Tomahawk Anti-Ship Missile Mission Profile A typical mission for a Tomahawk Anti-Ship Missile (TASM). After being launched from a ship or submarine, the TASM would cruise to the target area.
Once over the target area, it would fly a search pattern to look for targets and, if it found one, attack the target on its own.
Despite conventional thinking that fully autonomous weapons are yet to come, isolated cases of fully autonomous loitering munitions go back decades. In the 1980s, the U.S. Navy deployed a loitering anti-ship missile that could hunt for, detect, and engage Soviet ships on its own. The Tomahawk Anti-Ship Missile (TASM) was intended to be launched over the horizon at possible locations of Soviet ships, then fly a search pattern over a wide area looking for their radar signatures. If it found a Soviet ship, TASM would attack it. (Despite the name, the TASM was quite different from the Tomahawk Land Attack Missile [TLAM], which uses digital scene mapping to follow a preprogrammed route to its target.) The TASM was taken out of Navy service in the early 1990s. While it was never fired in anger, it has the distinction being the first operational fully autonomous weapon, a significance that was not recognized at the time.
In the 1990s, the United States began development on two experimental loitering munitions: Tacit Rainbow and the Low Cost Autonomous Attack System (LOCAAS). Tacit Rainbow was intended to be a persistent antiradiation weapon to target land-based radars, like the Harpy. LOCAAS had an even more ambitious goal: to search for and destroy enemy tanks, which are harder targets than radars because they are not emitting in the electromagnetic spectrum. Neither Tacit Rainbow nor LOCAAS were ever deployed; both were cancelled while still in development.
These examples shine a light on a common misperception about autonomous weapons, which is the notion that intelligence is what makes a weapon “autonomous.” How intelligent a system is and which tasks it performs autonomously are different dimensions. It is freedom, not intelligence, that defines an autonomous weapon. Greater intelligence can be added into weapons without changing their autonomy. To date, the target identification algorithms used in autonomous and semiautonomous weapons have been fairly simple. This has limited the usefulness of fully autonomous weapons, as militaries may not trust giving a weapon very much freedom if it isn’t very intelligent. As machine intelligence advances, however, autonomous targeting will become technically possible in a wider range of situations.