The Ukrainian military has used cluster munitions numerous times in its conflict with pro-Russian separatists, likely scattering deadly bombs that did not immediately explode and putting civilians at risk, Human Rights Watch said in a new report.

An investigation earlier this month found that the weapons were used more than a dozen times in fighting in eastern Ukraine, Human Rights Watch reported. Dozens of countries agreed not to use cluster munitions in a treaty signed in 2008, citing the indiscriminate nature of the weapon. The United States and Ukraine have not signed the treaty, with U.S. officials saying they have some legitimate uses.

“While it was not possible to conclusively determine responsibility for many of the attacks, the evidence points to Ukrainian government forces’ responsibility for several cluster munition attacks on Donetsk,” Human Rights Watch said, naming the city in eastern Ukraine that has been the site of heavy fighting. “An employee of the International Committee of the Red Cross (ICRC) was killed on October 2 in an attack on Donetsk that included use of cluster munition rockets.”

The weapons in question are surface-fired 220mm Uragan and 300mm Smerch cluster munition rockets. Each rocket contains smaller munitions, known as submunitions, that are designed to split up and explode separately. They can hit a wide area over hundreds of feet, and unexploded ordinance leave what are essentially landmines on the battlefield.

Human Rights Watch released the following photos to back their case, along with the video above.

Human Rights Watch said that the Ukrainian military has not responded to its allegations. The rockets have killed at least six people and wounded dozens. In one case, numerous submunitions hit the roof of a supermarket in Donetsk, leaving 15 impact sites, the group said.

The piece was updated to correct the U.S. position on cluster munitions.