Another way to view it, is that the West is waging a proxy war against Russia.
One might say that confrontation started with the West instigating a coup against democratically elected president of Ukraine and installing a pro-Western, pro-NATO regime. Another might say that it started when the West has methodically sabotaged all Russian actions to find peaceful solutions to the crisis in Eastern Ukraine and instead pushed for military options [1]. But these are technicalities.
There are two steps left before the possible direct military confrontation between the West and Russia. One step is the West officially sending troops to Ukraine, and another is Russia officially sending troops to Ukraine. Most probably, neither of them would be taken, but the situation is already dangerous enough.
Many say, that after we have left our military bases in Eastern Germany in exchange of the failed promise of NATO non-expansion, after many other actions of good will by USSR and then Russia, the West has been methodically showing us that it doesn't accept Russia as a peaceful partner.
By sanctioning Russia, by turning the blind eye on atrocities carried out by Kiev government, the West is waging the war against Russians, not only against Putin.
I do not know, how this crisis would end, but it is for sure going to set back our relations with the West for decades to come. And this is not all Putin's fault.
> Some things, however, are never allowed, such as sending military forces to invade and annex the sovereign territory of another nation.
Before the Russian actions in Crimea, there was a popular uprising against coup government.
The main powerhouse of the uprising was the city of Sevastopol, which was home for Russian military bases for hundreds of years. The residents of the city have in 20+ years never been allowed to have democratic elections of the mayor, because all Ukrainian governments felt that they would elect pro-Russian mayor. Instead, for 20+ years, they got mayors appointed from Kiev, some anti-Russian.
Crimea has de facto not been under the coup government control even before the Russian actions and was lost by Ukraine before it was gained by Russia, just after the coup government has started to pass one of it's first laws, the one that revoked the rights of the Russian-speaking regions to use Russian as second official language.
Personally, I don't like how Russia used it's military in Crimea and think that people of Crimea should have been allowed to fight for the independence themselves, possibly with some help. This was important technical issue and Russia has most probably got it wrong.
The situation is complicated by the fact that in reality there are different parts of Ukraine with completely different mindsets, preferences and interests.
But it is the Western Ukraine that has invaded Eastern Ukraine (with the help of US), not the other way around. This is the core point. This is why the people of Eastern Ukraine have the moral high ground in their fight. This is why Russia is not an aggressor.
P.S.
The coup government has also been waging war against the population of Crimea [2], "it's own population". And it also doesn't allow for every citizen from Crimea to freely enter Ukraine, some of them are sent back home [3] [4].
[1] Great article by Stephen Cohen (professor emeritus at New York University and Princeton University), which more or less summarizes not only my personal POW, but POW of many Russians and Ukrainians as well: http://www.thenation.com/article/180466/silence-american-haw...
[2] http://en.itar-tass.com/world/729666
[3] http://www.zerohedge.com/news/2014-04-17/ukraine-bars-entry-...
[4] http://korrespondent.net/ukraine/politics/3351043-ukrayna-ot...
