Ukraine Cease-Fire Is Falling Apart In The Pro-Russian Rebel Stronghold

Nice days into a truce between Ukrainian troops and Russian-backed separatists, fighting is raging.

The situation in the rebel stronghold of Donetsk in eastern Ukraine is "critical," according to local leaders. Rebels have been attempting to take control of Donetsk airport.

"We are still in a stage of war and the key aggressor is the Russian Federation," Ukraine Prime Minister Arseny Yatseniuk said over the weekend.

Here is a look at the battlefield, according to Ukraine's military. The increased fighting in Donetsk comes after Ukraine troops retreated from more than 60 miles of border in the southeast, which gives Moscow a clear gateway for intervention.

The concern in Kiev is that Russian-backed troops will try to take Mariupol, which would lead to a dangerous new phase of the war if fighting engulfs the pro-government port city of 500,000.

Compare that to the situation as of September 8.