"I am deeply concerned by what I've seen on the video [of the reported shelling] featured, apparently, to evidence Russia's growing involvement in the hostilities in Ukraine", - Breedlove wrote on his twitter account as reported by Censor.NET with reference to UNIAN news agency.
As reported earlier, a video of the alleged shelling has been taken and posted on YouTube by the locals of Gukovo town, Rostov oblast, Russia. On this video one can see BM-21 Grad launchers, located near the Russian town, firing missiles towards, apparently, Ukraine's territory.
Later, the precise location of the missile launchers had been identified as the one in Rostov oblast, and related proof was posted on the Internet by military analysts. Unique features of the local terrain as well as the calculation related to sound produced by the launch have helped to pin down the location of the culprit MRL Grad.
[voice on the video] "Here is the sketch showing the coordinates of the firing position of the Russian MRL Grad, which shelled Ukraine's territory… and here you can see the exact distance to the firing position from the place where the original video was taken. The distance is 2 km [1.2 miles], [we calculated] using the speed of sound method for calculating distances".