War in Ukraine?

I read through some threads, some wiki articles, and this thread. But I still don't understand why this is such a 'hot' issue for the U.S. to be concerned about. Even considering Russia's involvement in this issue, what advantages would the Ukraine give Russia if they decided to annex the country via military proxy that would lead Russia towards being more competitive in terms of economic and military strength? As far as I know, there are more flaws than draws if Russia pushes ahead in terms of the long term benefits since it will give the U.S. an excuse to launch sanctions against Russia and cripple them economically. That leads to the U.S. benefiting from a hostile Russia move towards the country since it will likely loosen the country from Putin's influence and allow the U.S. to gamble on another president that would be more open towards cooperation with their foreign policy

Russia desperately needs Ukraine to fulfill their economic and military goals for the future. I'm sure you have understand why Putin desires Crimea, but he wants the rest of the Urkaine as well. Russia has for a while now been seeking a Eurasian bloc that could compete outside of Western influence. Ukraine is also an important part of that as an important food source for China and Russia.

As far as all of these sanctions letting the US get the political upperhand on Russia, I think that is a misconception. There is a pretty interesting article in the New York Times (yes, that's a link and not an ad) that talks about growing Anti-American/Western sentiment and how some Russian elites are using these sanctions as an excuse to move towards closer ties with China. As far as public opinion goes, I do not think Putin is very concerned.