While the United States and other Western countries condemn pro-Russian separatists in eastern Ukraine for downing Malaysian Airlines flight 17, and the subsequent handling of the crash site and remains, a new Human Rights Watch report released Thursday accuses Ukrainian government forces of indiscriminately rocketing civilian areas.

Between July 12 and July 21 Ukrainian government forces have killed more than 15 civilians and wounded countless others in at least four separate attacks with unguided ‘Grad’ rocket attacks on separatist-controlled territory.

“Grad rockets are notoriously imprecise weapons that shouldn’t be used in populated areas,” said Ole Solvang, senior emergencies researcher at Human Rights Watch. “If insurgent and Ukrainian government forces are serious about limiting harm to civilians, they should both immediately stop using these weapons in populated areas.”

The use of unguided rockets in populated areas is a violation of international and humanitarian law and may amount to war crimes, Human Rights Watch reports.

The Grad, which means “Hail” in Russian is a 40-tube multiple-launch rocket system that has been in use since the 1960s. The 122mm rocket can weigh anywhere between 66kg and 45kg and reach a range of up to 20,000 meters. The high explosive rocket variant has a warhead that weighs 18.4kg, meaning that a Grad Battalion of 18 launchers can deliver 46,000kg, or roughly 10,000 pounds of explosives onto a single target.

Though the Ukrainian government denies the use of Grad rockets, a Human Rights Watch investigation has found that both government and separatist forces have used the system in and around Donetsk.

In a post-blast analysis of the four attacks, Human Rights Watch identified distinct patterns consistent with rocket attacks, including the shape of impact craters and damage to building facades that indicate a lateral rocket strike as opposed to a vertical hit consistent with artillery shelling.

While the report condemns the use of the rockets by government forces, it also flags separatists for not taking measures to avoid encamping in densely populated civilian areas.

“Ukrainian authorities should order all their forces, including volunteer forces, to immediately stop using Grads in or near populated areas, and insurgent forces should avoid deploying in densely populated areas,” Solvang said. “Commanding officers on all sides should recognize that one day they could face legal consequences for their actions.”

Fighting has intensified in recent weeks as Russian troops have moved within 5 miles of the Ukrainian border and reports have indicated that Russian artillery units have been shelling Ukrainian forces from within Russia.