I've been saying this for quite some time. Crimea was part of Russia for hundreds of years before the Ukrainian Nikita Khrushchev gave it to the Ukraine in 1954 as part of his bid to succeed Joseph Stalin. Putin is methodically putting back together Greater Russia (not exactly the old Soviet Union), comprised of areas with small majorities or large minorities of ethnic Russians. This does not bode well for the Balkans, and is eerily reminiscent of Adolph Hitler's pre-war annexations of Austria and the Sudetenland.
More like Hitler marching into the Rhineland. Donetsk, would be the Sudetenland.