Russia-Ukraine conflict: How the showdown between neighbors came to be

Russian scholar David Satter details the long history between Russia and Ukraine in "Fox Nation 101: The Ukraine Crisis"

But the fall of the Soviet Union centuries later was the ultimate turning point, bringing freedom to Crimea and Ukraine – a nation that had differentiated itself from Russia with European influence and "national feelings," Satter said.

The scholar explained that multiple treaties were signed with Ukraine, all of which validated the existing borders with Russia and Crimea. Meanwhile, the communist governments of former Eastern European satellite countries were overthrown and granted independence, including East Germany which was reunited with the west at the destruction of the Berlin Wall.

The countries in the belt between Germany and Russia soon recognized their need to join NATO, Satter said, as they stood vulnerable if Russia were to regain power again.