just as the large Black Sea fleet is based in Crimea, Russia has for a long time maintained a large fleet and military bases in Kaliningrad and the region. these were things that were not negotiable

Why didn't it become independent or part of a neighboring country when the Soviet Union dissolved?

Undisciplined

There is a road connection there that is secured by the military.

TomK

econ

Russian Economy Booms Amid Eurozone Recession

I've always wondered how Russia has managed to hold on to Kaliningrad. 

Are they isolated or is it easy to travel in and out?