Gas

What I said yesterday, unfortunately, may not be really relevant nowadays. If Turkey becomes part of Europe, the Black Sea is less of a consideration - because of the strategic position of Istanbul.

(Turkey has been on waiting list for years but is not yet a member of the European Union. If Ukraine falls into the hands of Vladimir Putin, I am sure the process would not take long.)

In that case, why should the land on the border be so important?

Because of Gazprom.

Yes, I mean the largest extractor of natural gas and actually one of the largest companies in the world. It accounts for over 15% of the gas production worldwide (over 80% of Russian production), and up to 8% of Russia's gross domestic product. Natural gas is extracted from Yamburg and other freezing parts of Russia and exported to Europe via the Unified Gas Supply System (UGSS), the largest gas transmission system in the world.

Unfortunately (to Russia), UGSS is much under the control of Ukraine.

The situation is quite obvious if you take a look on the map here: http://upload.wikimedia.org/wikipedia/commons/d/d7/Major_russian_gas_pipelines_to_europe.png

PS. Ukraine literally means the land on the border. It was the name coined by Polish invaders in the 16th century.