Where is the best analysis of the situation in Ukraine?

There can be none. It has been only like a day. Wait a week.

In the command structure of the Russian Forces right now.

See chapter 6 of this book that was published in 2009 (The Next 100 Years by George Friedman):

http://www.mysearch.org.uk/website1/pdf/715.2.pdf

If nothing else, it outlines the strategic situation that is providing some of Putin's underlying motivation, namely, declining Russian population and encroaching NATO boundaries.