Ilovaisk was once a sleepy small town in eastern Ukraine, but by mid August this year war was knocking at the door as fierce fights between pro-Russia rebels and Ukrainian forces raged through surrounding villages and countryside. The distant explosions which illuminated the night sky on August 14, however, looked nothing like the grad rocket and mortar fire that the locals had come to recognize.

At first, the town's residents thought the Ukrainians were just celebrating a victory. "It seemed like they were setting off fireworks after retaking a nearby village from the militia," 52-year-old Elena Sychova, the caretaker at school 14, told VICE News. "But then we realized it wasn't stopping. It was getting closer and closer to us. It was like a rain of fire."

A subsequent investigation by VICE News, including an independent expert analysis of retrieved rocket remnants by Armament Research Services (ARES), showed that the "fireworks" were in fact thousands of incendiary elements cascading out of a Soviet-era 9M22S rocket in mid-flight.

Up to 40 9M22S rockets can be fired in approximately 20 seconds by the 9K51(aka BM-21 **) "**Grad" Multiple Launch Rocket System (MLRS). Ignited at the point of ejection, the 180 hexagonal-shaped shells packed into the rocket's 9N510 warhead each contain a thermite-like substance and burn furiously as they plummet to the ground.

Although the elements are small — 1.02 x 1.65 inches or 2.6 x 4.2cm — they reach a blazing temperature. Most thermite compositions ignite at temperatures in excess of 3,992 degrees Fahrenheit (2,200 degrees Celsius). The heat is sufficient to reduce the outer ML-5 magnesium alloy casing to ash.

Photograph showing the incendiary elements from the 9N510 warhead in various conditions. From left to right: intact, partially burnt, and reduced to ash. Images via Harriet Salem.

The night of August 14, around 10pm, local residents across Ilovaisk — which at the time was under rebel control — report hearing a number of unusual-sounding explosions in quick succession and what appeared to be giant "fireworks" coming from the south-west.

Alexander, a 44-year-old security guard, was about to go to bed when he heard the rapid series of booms. "It seemed far away, so I didn't worry. My wife and kids were already living in the bomb shelter under the cultural center at this time, but I stayed here to protect the house," he told VICE News.

But by the time Alexander reached his back gate the "massive fireworks" he at first saw out the window had turned into "balls of fire falling from the sky." The ground in his backyard soon began burning. "In the first moment I thought to lay on the floor but then I realized if one hit me I would be burned to the bone, so I ran back inside," he said.

'There was no clear military objective, we saw civilian houses burned. Any military advantage perceived as being gained by using these weapons is outweighed by the humanitarian consequences.'

Alexander and other residents of Komsomolskaya Street said that five to ten minutes after the "fire" stopped falling, the roofs of buildings also started catching alight. "On this street we were lucky we had a big tank of water in one of the neighbor's gardens so we worked together using buckets to put out the fires," Alexander told VICE News. "They started firing Grad rockets shortly after, while we were still putting out the fires. Bombardment was near constant at this point. We managed to save four houses on this street but one burned down. After this fire attack I'd had enough. I took my stuff and moved to the bomb shelter at about 4:30am that morning."

That night at least eight houses were completely destroyed and dozens more damaged by the "fire" that fell from the sky.

In all the locations where buildings were identified by locals as starting to burn in the minutes after the attack, VICE News found telltale charred hexagonal remnants nearby and multiple sites of small patches of charred earth around the area of the primary fire.

The very nature of incendiary attacks typically makes identification of the weapons used exceptionally difficult. Most vital evidence, including the munitions remnants, is normally destroyed or damaged beyond recognition in the blazes that follow.

In the case of Ilovaisk, however, video footage filmed on the night of the attack from outside the nearby village of Zelene — provided to VICE News by a local resident — alongside multiple eyewitnesses testimonies, gave unique clues that allowed for the identification of the likely firing position approximately 11 miles (18.1 kilometers) south-west of the town.

Mobile phone video footage provided to VICE News appears to show at least a couple of dozen 9M22S rockets exploding over Ilovaisk. It w__as filmed on the night of August 14 from the southern edge of Zelene village, 0.7 miles to the north.

Overlooking the vast stretches of the region's mostly flat landscape, around one mile short of the 9M22S's maximum range from Ilovaisk, VICE News found an abandoned Ukrainian hilltop camp. Here, buried under leaves and amid the deserted trenches, litter of bullet casings, and scattered ammunition boxes, was vital evidence tying the site to the attack on Ilovaisk, including charred earth, intact hexagonal elements, and several remnants from unexploded and misfired rockets.

The rocket body of a 9M22S found by VICE News at an abandoned hilltop Ukrainian position approximately 11 miles from Ilovaisk. The red stripe denotes an incendiary weapon according to the Eastern Bloc munitions marking system.

The 9M22S rocket engine found by VICE News at the abandoned Ukrainian position.

When analyzed by ARES experts, the components were matched to the unusual and distinctive remnants of the type of weapon found by VICE News in Ilovaisk, making the windy hilltop spot the most likely origin for the "rain of fire" over the nearby town.

The view inside an unexploded cargo section of a 9N510 warhead found by VICE News at the abandoned Ukrainian position. 180 incendiary elements, seen here in a honeycomb formation, are packed inside the warhead.

The rocket engine and stabilization fins of the 9M22S laid out next to the rocket body. All components were found at the abandoned position approximately 11 miles from Ilovaisk.

Documented use of fire-starting weapons in Ukraine dates back to fighting in Sloviansk in June. However little empirical research has been done into the types of munitions that may have been used. At the time of the first attacks, Russian media widely, and erroneously, reported the weapon was "white phosphorus-based."

Famously used by the US in Vietnam and Israel in Gaza, white phosphorus has attracted international condemnation for its indiscriminate nature and well-known deadly and poisonous effects, making its alleged use by Ukrainian forces in Donbas an easy propaganda point-scorer for Russia.

However, expert analysis of video from several incendiary attacks filmed in eastern Ukraine, including the footage obtained by VICE News of the attacks on Ilovaisk, has concluded that the weapon in use is not consistent with the accounts in the Russian media. "White phosphorus is typically characterized by a significant, ongoing output of brilliant white smoke, which is absent in these cases, suggesting it is more likely an incendiary or pyrotechnic," ARES's director and incendiary weapon researcher, N.R Jenzen-Jones, told VICE News.

'The international community needs to take action because existing laws are not adequate.'

In comparison to many white phosphorous munitions, little is known about the 9M22S rocket and the 9N510 warhead. According to insider source information provided to ARES, the only prior confirmed use of the rocket is in Soviet-era wars in Afghanistan, but the weapon is also suspected to have featured in more recent conflicts including in Libya and Chechnya.

Developed and produced in the secretive arms programs of the Soviet Union, where incendiary weapons continued to be a mainstay long after they had fallen out of favor with Western armies, the 9M22S/9N510 and other munitions of that era have remained largely shrouded in mystery, even to the expert community.

"Many of these weapons developed under the Soviet Union we know little to nothing about," Mark Hiznay, a senior arms researcher with Human Rights Watch (HRW), told VICE News. "Now after years gathering dust in stockpiles they're popping up, in Libya, in Syria and, of course, in Ukraine which has its own stockpiles, and we have to try and figure out exactly what's going on and how they work," added Hiznay, who has conducted field research in eastern Ukraine's battlefields and other conflict zones.

One thing experts can say for sure, however, is that the 9M22S/9N510 can start deadly blazes in a matter of minutes. "These types of weapons are designed to set fire to targets of military importance and are typically employed against infrastructure such as ammunition and fuel dumps, although they have also been employed in the anti-personnel role. When fired into any infrastructure, including built-up residential areas, if a sufficient quantity of flammable material is present, there is the potential for a fire to start. The higher the density of incendiary elements, the greater that chance typically is," Jenzen-Jones explained.

Incendiary weapons have long been used on the world's battlefields. The use of fire-tipped arrows was documented as far back as 500BC in the first-ever known military manual, The Art of War. Since then almost every fighting force, from the Spartans to the Soviets, has used fire warfare.

Indeed, one of the factors that has made the use of incendiary weapons so persistent and valuable throughout history is not only fire's ability to cause death and widespread damage, but also its capacity to incite fear and reduce morale, not only in armies but also among local populations deemed hostile to the attacking force. One such example of specifically targeting civilian areas with incendiary weapons is the firebombing of German cities by Britain and the US during World War II.

Yet, despite the widely acknowledged ability of incendiary weapons to kill, terrorize, seriously injure, cause psychological trauma, and devastate infrastructure, they remain among the most poorly regulated category of arms under international laws of war.

'Many of these weapons developed under the Soviet Union we know little to nothing about. Now after years gathering dust in stockpiles they're popping up, in Libya, in Syria and, of course, in Ukraine.'

Protocol III of the Convention on Certain Conventional Weapons (CCCW), which 108 states including both Russia and Ukraine are party to, is the main legal framework governing the use of incendiary warfare. It proscribes targeting civilians with weapons that have a primary function of starting fires. However, while the legislation also prohibits the use of air-to-surface incendiary munitions against military targets if they are in close proximity to concentrations of non-combatants, it does allow the use of surface-to-surface incendiary munitions, such as the 9M22S/9N510, in such circumstances.

Speaking by telephone from Geneva where he is lobbying on behalf of HRW to increase the scope of international regulation of incendiary weapons, Hiznay, who has visited the site in Ilovaisk, told VICE News that not only in Ilovaisk but in countless conflict zones across the world, civilians are dying from being caught in the crossfire.

"The international community needs to take action because existing laws are not adequate... The facts on the ground belie theoretical claims of (the Ukrainian) government. There was no clear military objective (to the attack in Ilovaisk), we saw civilian houses burned. Any military advantage perceived as being gained by using these weapons is outweighed by the humanitarian consequences," he added.

Jenzen-Jones of ARES said there is also a need to pay greater attention to the outdated delivery systems being used to launch weapons such as 9M22S. While many surface-to-surface munitions are more accurate than air-to-surface munitions, there are exceptions to the rule and the 9M22S/9N510 — an unguided rocket delivered by an outdated 9K51 MLRS system — is a case in point, he explained.

"Like many older MLRS systems, the 9K51 is not an especially accurate weapon," he said. "It is designed to bring maximum force to bear on area targets, saturating an area with a rocket barrage. It is not designed for accurately engaging point targets in the same way that many modern systems are. The 9M22S is a free flight (unguided) rocket, and considerably less accurate than the precision guided munitions we would expect many modern militaries to employ when engaging military targets in built-up, civilian areas."

Back in Ilovaisk, the costs of not only the incendiary attack, but of the town's heavy bombardment by both warring sides, are evident everywhere as residents desperately try to and fix the many damaged houses before the winter snow arrives.

The house of Svetlana Danshin and her son, one of those burned to the ground on August 14, is beyond repair. All that still stands are four charred walls. "We lost everything but what we had on our backs that night," said 19-year-old Denis Danshin, who traveled with his mother through the dark, war-torn countryside from a village where they had taken refuge, after neighbors phoned to say their house was on fire. As he talked, the family's shell-shocked dog snarled amid the charred remains. "My mother was hysterical… We thought we could salvage something, but there was nothing left to save, just ash and rubble... The only good thing I can say, is thank God we were not inside."