Russia has long been a paranoid land power. It's huge, mostly flat, and wide open to invasion. Just to name a few examples, it was invaded by the Mongols in the 13th century, Napoleon in the 19th, Nazi Germany in the 20th, and has been recently squeezed by NATO expansion in the former Soviet bloc. These events seared themselves into the Russian psyche. They breathe better with buffer states.

Pity the Vassals of Moscow (4 March 2014)