The territory controlled by pro-Russian rebels in the Donbas region of Ukraine has varied significantly. By early July they held large parts of Luhansk and Donetsk, but they were then driven back by the Ukrainian armed forces. They lost more ground after the shooting down of Malaysia Airlines flight MH17. In late August Russian forces crossed the border in large numbers and pushed the Ukrainians back. The rebels have now regained much of what they earlier lost.
Link to article: www.economist.com/news/europe/21620263-significant-variations?fsrc=rss|eur