What happened in Crimea is not a "invasion", Crimeans have literally wanted to join Russia for decades now. They voted overwhelmingly for independence from Ukraine in 1994, but Ukraine strong armed them, removed their president, tore up the constiution and wrote new laws to keep Crimea.

Russia has had troops in Crimea for decades now, they are by treaty allowed to have 25,000 troops there and close to 17,000 were there when the democratically elected government that Crimeans voted for became overthrown through a violent coup in Kiev and replaced with one that Crimeans overwhelmingly voted against.

The Partition Treaty on the Status and Conditions of the Black Sea Fleet was a treaty signed between Russia and Ukraine on 28 May 1997 whereby the two countries established two independent national fleets, and divided armaments and bases between them.[2][3] Under the treaty, the Black Sea Fleet that was located in the Crimean peninsula at the time, was partitioned between Russia (81.7%) and Ukraine (18.3%), with Russia maintaining the right to use the Port of Sevastopol in Ukraine for 20 years until 2017.[4] The treaty also allowed Russia to maintain up to 25,000 troops, 24 artillery systems, 132 armored vehicles, and 22 military planes on the Crimean peninsula.

http://en.wikipedia.org/wiki/Partition_Treaty_on_the_Status_and_Conditions_of_the_Black_Sea_Fleet

Putin of course did take advantage of the situation, however Crimeans overwhelmingly show support for joining Russia, even by Western poll companies like Pew Polls and Gallup! They finally got what they wanted for decades, only 4% of Crimeans are opposed to being part of Russia according to UKRAINIAN polling!

It seems nobody here gives a fuck what Crimeans want, as long as Crimea is controlled by the West.