Marines Conduct First Field Test Of ‘Non-Lethal’ Mortar Rounds Full of Flash-Bangs

The U.S. Navy’s biennial Rim of the Pacific exercise, or RIMPAC, typically offers an opportunity for the U.S. military as a whole, as well as its foreign allies, to test out new, unusual, and still-in-development capabilities. The most recent iteration of the event saw the first-ever field test of an 81mm mortar round that’s supposed to disperse crowds and distract opponents rather than kill anyone, which could be extremely valuable for American forces taking part in peacekeeping, humanitarian relief, embassy defense, or even combat missions.

According to Stars and Stripes, Marines from 1st Battalion, 3rd Marine Regiment fired 56 prototype Non-Lethal Indirect Fire Munitions (NL-IDFM) at the Pohakuloa Training Area in Hawaii earlier in July 2018. The Joint Non-Lethal Weapons Directorate, the Pentagon’s centralized less-than-lethal project office, is in charge of the program, which has included input and support from all of the services.

“Currently, the armed forces are unable to deliver non-lethal effects at extended ranges,” Michael Markowitch, an engineer at the Army’s Picatinny Arsenal said in 2016 shortly after he and his colleagues received a patent for the 81mm mortar projectile’s design. “Our goal was to develop a mortar that would be capable of delivering a non-lethal payload at ranges typical of mortar systems.”

The round’s design, as it stands now, consists of a modified 81mm M853A1 illumination shell body containing 14 submunitions. Each one of these is a stun grenade, or “flash-bang,” that delivers a painful 180 decibel bang – which could cause permanent hearing loss if a person had to endure it for a sustained period – and a blinding 1 million candela burst of light – a common candle gives off about one candela for comparison – to anyone in a five foot radius.

An annotated cutaway of the NL-IDFM mortar projectile showing its major components., US Army

When the round hits an altitude of around 650 feet, it breaks in half, with parachutes pulling it apart at both ends. The flash-bangs, each with a streamer tail to slow their descent, then fall onto the target area. Engineers added delay fuzes in each one of the submunitions to do their best to makes sure they hit the ground before going off for maximum effect. A single round can effectively cover an area of more than 4,000 square feet, according to the Army.

Otherwise, the NL-IDFM functions the same way as a standard M853A1. It has a range of between 490 and 1,640 yards, depending on the number of propelling charges the mortar crew attaches to the round.

An annotated image from an earlier test showing the NL-IDFM in action., US Army

This is a significant stand-off range compared to most less-than-lethal systems, which typically require the operator to be extremely close to their target. As such, it could expand U.S. forces options short of using lethal force in a variety of scenarios.

The most obvious would be if a small number of American troops found themselves trapped by a potentially violent crowd of civilians during a non-combat or combat mission. Rather than having to wait for additional support, a length of time where tensions and the possibility of making a deadly mistake could increase, they could quickly call for a less-than-lethal fire mission and then attempt to leave the area.

The rounds could also be valuable in protecting an embassy or other U.S. government facility abroad during a period of civil unrest, a mission the U.S. Marine Corps, in particular, is often called on to perform. Troops can employ the NL-IDFM “selectively” in order to “deny an area, warn or move individuals, and suppress threats,” according to an official Marine Corps fact sheet. So, instead of relying on short-range systems to deter individuals once they’ve gotten close to the site itself, troops could seek to dissuade crowds that might be blocks away from even getting near the buildings.

There might even be a role for the rounds in more traditional combat situations. The light and noise could easily draw the attention of enemy forces away from the main force of an attack at a critical moment or otherwise confuse and disorient them.

“They’ll be disoriented … and while their heads are hunkered down making sense of what happened we can assault,” U.S. Marine Corps Sergeant Joshua Jackson, in charge of one of 1-3rd Marines’ smaller 60mm mortar sections, told Stars and Stripes after the evaluation during RIMPAC. “It would be much more effective at night … once that flash goes off you’re going to be night blind.”

There are also plans for additional features to go into the final design. As of 2016, there were also plans to add an invisible marking dye, visible only under an ultraviolet lamp or “blacklight,” which personnel could use to identify violent protesters who might flee the scene.

A description of the desired marking dye capability from a 2016 US Army briefing. , US Army

This could also be useful in a limited combat operation to uncover insurgents who might disperse after a firefight and go back into hiding among the local population. The U.S. Navy briefly considered a similar concept during the Vietnam War using what unfortunately turned out to be a carcinogenetic chemiluminescent chemical.

The Joint Non-Lethal Weapons Directorate has also expressed an interest in the past in developing a similar round for 60mm mortars, too. In the mid-2000s, the Army even experimented with a 155mm howitzer shell that featured a payload of what were essentially over-sized stink bombs.

The service never revealed exactly what compound or compounds it used in these experimental XM1063 Non-Lethal Personnel Suppression Projectiles or what they smelled like, but they fired off the last of them in a test sometime between 2006 and 2007, according to information I previously obtained through the Freedom of Information Act. This effectively ended that program and the Army does not appear to have revisited it since then. The U.S. military did have tear gas artillery shells in inventory for a time, but finally disposed of them completely in the 1990s.

A description of the XM1063 155mm Non-Lethal Personnel Suppression Projectile., US Army

Unfortunately, as with any less-than-lethal system, the NL-IDFM program has struggled to find the right mix of useful effects while still ensuring that the rounds won’t seriously injure or kill individuals in the target area. The U.S. military has been working on the project in one form or another since 2000 and there were two previous tests of the shells in a more controlled environment in 2014.

By that time, engineers had settled on the flash-bang payload over a host of different options, including whistles, smoke and tear gas canisters, and substances that produced unbearably bad odors, indicating that it provided the best combination of safety and utility. The dual-parachute concept also prevents individuals below from getting showed by parts of the mortar shell body after it breaks open.

Wind tunnel models of proposed 81mm less-than-lethal mortar shell body and fin designs circa 2000., US Army

The tests at Pohakuloa show that the system still needs more work, with Marines reporting that approximately one in 10 rounds did not function properly. According to Stars and Stripes, the shells wobbled oddly in flight, as well, and the parachutes did not always seem to deploy completely.

Nathan Rush, a munitions capabilities integration officer, told Stripe that there are at least six more months of developmental tests left to go, followed by an estimated two years of qualification testing. The goal is for the round to go into mass production in 2021, which will be more than two decades after the Joint Non-Lethal Weapons Directorate first started working on the concept.

Hopefully, U.S. troops won’t have to wait much longer for what could be a useful and novel capability to add to their existing options for tackling complicated operations.

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Joseph Trevithick

Deputy Editor

Joseph has been a member of The War Zone team since early 2017. Prior to that, he was an Associate Editor at War Is Boring, and his byline has appeared in other publications, including Small Arms Review, Small Arms Defense Journal, Reuters, We Are the Mighty, and Task & Purpose.