Earlier today, Ukrainian president Petro Poroshenko accused Russian troops of entering Ukraine, and NATO issued a statement saying that they were tracking well over 1,000 Russian combat soldiers operating heavy weaponry within Ukraine's borders. The announcements follow months of fighting between Ukrainian government troops and pro-Russian rebels in eastern Ukraine—reportedly supported by Russian troops nearby. Ukrainian government forces had been regaining territory held by rebels in recent weeks, only to have the separatists open up battles on new fronts in the region. Caught in the middle is the civilian population, suffering hundreds of injuries and deaths as a result of massive shelling campaigns. Russia continues to deny direct involvement, even explaining that some of its captured servicemen were in Ukraine "by mistake." Below are images from eastern Ukraine over the past few weeks, as the situation may soon escalate even further.