In August 2018, suicide attack drones grabbed headlines when used in an assassination attempt against Venezuelan president Nicolás Maduro. Similar drones were used by ISIS in Iraq and Syria to attack coalition and regime forces. While some media outlets have suggested that ISIS has pioneered the use of the “suicide drone,” regular militaries have been using suicide drones for nearly three decades under a different name: Loitering Munitions.
While the loitering munitions fielded by regular militaries are significantly more advanced than the modified drones used by ISIS, the basic concept is the same. An explosive warhead on a flying unmanned air vehicle (UAV) is flown into a target to deliver precision strike effects.
By most accounts, Israel pioneered the development of loitering munitions in the late 1980s or early 1990s as an anti-radar solution. The Israel Defense Forces (IDF) was always a pioneer in UAV usage—they reduced casualties and political risk, key considerations with a conscripted force.
The IDF realized the potential of UAVs in the anti-radar role following its experience during the 1982 Lebanon War. Israeli UAVs were used for reconnaissance and as decoys to destroy multiple Syrian Surface to Air Missile (SAM) sites in Lebanon’s Bekaa Valley, in what was called Operation Drugstore.
Israeli designers probably thought up the idea of a loitering munition following Operation Drugstore. During the operation, simple Delilah decoy drones were launched in large numbers, masquerading as an Israeli strike force. Once the Syrian radars switched on to engage the drones, Israel fired a variety of anti-radar missiles adapted for ground launch and launched a real air attack on the radars.
The first loitering munition, the Israel Aerospace Industries (IAI) Harpy, combined the drone and the anti-radar missile. The Harpy would be launched and enter a searching pattern, waiting for a radar to activate. If a radar activated, the Harpy would then home in on and destroy the radar using a blast fragmentation warhead in its body. The Harpy could loiter over the battlefield for up to six hours after launch.
The Harpy was revealed to the public in 1990. Turkey and India bought the Harpy later that decade. IAI also developed another loitering munition, the CUTLASS in conjunction with Raytheon in 1999. Development of these systems continued throughout the 2000s, but the systems largely were not ready for the spotlight. The Delilah decoy drone also was turned into a loitering munition around this time, incorporating technology from the Harpy and a true warhead.
However, the loitering munition would only really take off in the 2010s as sensor technology improved and drones got smaller. Improved camera technology meant that loitering munitions could see and target anything visible on the battlefield, not just radars. Loitering munitions, piggybacking off of advanced drones, got smaller to the point where they could be carried and launched by individual soldiers.
The United States fielded its own miniature loitering munition in 2012 with the AeroVironment Switchblade. The Switchblade was used by the U.S. Army in Afghanistan to target “high value targets,” whether it be insurgent leaders, mortar teams, or insurgents traveling in a vehicles. While limited in endurance, the Switchblade could loiter over the battlefield if the target was not immediately visible after launch.
In this role, the loitering munition is seen to provide a more precise alternative to guided artillery and traditional drones to a small unit leader. Loitering munitions are cheaper than dedicated missiles fired from drones and have faster “response” times, being able to be launched by soldiers on the ground. Being directly guided by cameras on board, they are far more accurate than guided artillery, landing within meters of a target compared to tens of meters for a laser guided artillery shell.
U.S. procurement of loitering munitions stepped up in 2018, with the Marine Corps launching a program to procure them to replace their 120mm mortars as an organic precision fire capability. SOCOM is also looking to add loitering munitions to boats used by special operations forces.
But the loitering munitions that have seen the most combat are versions of the original Harpy. IAI continued upgrading the platform throughout the 2000s, giving it electro-optical sensors, greater endurance, and a revised wing design. The platform, now called Harpy NG or Harpy 2, was sold to the Azerbaijani Armed Forces sometime in the 2010s, which used it during a flare-up in the Nagorno-Karabakh region in 2016.
Loitering munitions have also returned to their original role during events in 2018 and 2019 when they were used by the IDF to destroy Syrian Pantsir-S1 SAM batteries. While it’s unsure whether the munitions used in these strikes were Harpy 2, SkyStriker, or Delilah, loitering munitions remain effective in their original role.
Regardless, loitering munitions are likely to be fielded by more and more militaries in the 2020s given their versatility and effectiveness. Development is speeding up, with innovations like interchangeable warheads on Poland’s Warmate loitering munition and swarm tactics with the U.S. Navy’s LOCUST test drones.
Given their low radar, visual, and thermal signatures, loitering munitions are very hard to track and kill. Success on a future battlefield may very well be determined by which side can use loitering munitions to the greatest effect.
Charlie Gao studied Political and Computer Science at Grinnell College and is a frequent commentator on defense and national security issues. This first appeared in January 2019.