KRAMATORSK, Ukraine — Russia has made liberal use of one of its most fearsome conventional weapons in the fighting in eastern Ukraine, according to Ukrainian military commanders, medics, British officials and videos from the battlefields.
The weapon, a track-mounted rocket artillery system nicknamed Solntsepek, or the Heatwave, fires thermobaric warheads that explode with tremendous force, sending potentially lethal shock waves into bunkers or trenches where soldiers would otherwise be safe.
“You feel the ground shake,” said Col. Yevhen Shamataliuk, the commander of Ukraine’s 95th Brigade, whose soldiers came under fire from Russia’s Heatwave weapon in fighting this month near the town of Izium.
“It’s very destructive,” Colonel Shamataliuk said. “It destroys bunkers. They just collapse over those who are inside.”
The United States and other militaries also deploy thermobaric warheads in missiles and rocket-propelled grenades. And Ukraine’s Army said on April 5 that it had fired Heatwave thermobaric rockets from a captured system back at Russian troops, intending to burn them with their own weapon, in fighting near Izium.
Thermobaric weapons are not banned, and they are not addressed in the Geneva Conventions, a series of international agreements that govern warfare. Russia’s military has deployed the Heatwave weapon in the war in Syria, but its use in Ukraine has become systematic, according to the Ukrainian military and video footage of strikes on towns in eastern Ukraine.
Such explosives, also called fuel-air bombs or vacuum bombs, scatter a flammable mist or powder that is then ignited and burns in the air. The result is a powerful blast followed by a partial vacuum as oxygen is sucked from the air as the fuel burns.
Ukrainian soldiers who have been caught in the explosions and survived a mix of burns and concussions, said Sgt. Anna Federchuk, an ambulance medic based in Kramatorsk, in eastern Ukraine, who has treated casualties from Heatwave strikes.
“It’s a mixed diagnosis,” she said of the typical casualty from a Heatwave explosion. “The burns are deep and severe.”
The Russian weapon carries a box of rockets atop a tanklike tracked vehicle. It can fire single rockets or a terrifying volley. Still, like many Russian weapons deployed in the Ukraine war, the Heatwave system may not be as effective or decisive in combat as Russian military propaganda suggested it would be.
Developed in the 1980s and once viewed as an awesome and feared invention of late-Soviet military prowess, the Heatwave, formally known as a Tos-1 heavy flamethrower, has drawbacks.
With a range of only six miles, it must be driven close to the front to fire. There, it has been vulnerable to Ukrainian ambushes. In March, a drone video showed Ukrainian soldiers blowing up a Heatwave weapon during an ambush outside the Kyiv suburb of Brovary.
The strike on the vehicle sent its rockets sailing out into the Russians’ own column of armored vehicles, though it was unclear whether any were destroyed.
Their use near the front has also allowed Ukraine to capture some of the weapons. Videos have appeared online purporting to show Ukrainian tractor drivers towing captured Heatwave weapons away from the front. Ukrainian soldiers have claimed on social media to have seized five of the weapons systems as trophies.
Ukraine’s military has also said that the Russians have friendly fire incidents with the Heatwave as it sprayed out highly destructive but unguided rockets.
“The leadership of the 97th Infantry Battalion expresses its satisfaction with the actions of the Russian occupiers,” the Ukrainian military said in a sarcastic statement on May 8 after what it said was a friendly fire strike in the Zaporizhzhia region that killed Russian soldiers. “Such actions are positively perceived and supported in every way by the Ukrainian military. We understand there is a tradition of cooking shish kebabs in May.”
Maria Varenikova contributed reporting.