Overnight the militants shelled the village of Pisky of Donetsk region when the OSCE Special Monitoring Mission (SMM) was inspecting that region, U.S. Department of State reported.

"Yesterday Russia-backed separatists also launched an attack on the village of Pisky, where OSCE monitors were inspecting a checkpoint. We condemn this attack, which ended up – injured up to seven Ukrainian troops and placed the OSCE monitors in danger. We commend the OSCE for continued monitoring, even at the risk of personal harm, and we reiterate our call for unfettered access for OSCE monitors," said U.S. Department Deputy Spokesperson Marie Harf said at a press conference on Monday.

She stressed that Russia and the separatists it backs will face increasing costs if they do not implement their Minsk commitments.

"On Ukraine, we continue to see an increasing disparity between what Russia and the separatists say and what they do," Harf said adding that such kind of disparity between words and deeds threatens the Minsk agreements and stability in the region.

"Russia and the separatists claim to be honoring the ceasefire, but in reality they are violating it on a regular basis and are encroaching further beyond the ceasefire line, including recent attacks on an important bridgehead in northern Luhansk," the deputy spokesperson said.