Well, to me anyway....
In 2004, Ukraine was the fifth-largest importer of natural gas in the world. Belarus was the tenth-largest. In 2005, Belarus had dropped out of the top-10, not because it had reduced its consumption (net imports had increased), but because some countries, like the Netherlands, had increased their import requirements more dramatically. Ukraine remained fifth, and had increased its imports of gas by nearly 15%. Together, they absorbed nearly 40% of Russia's exports, and nearly 10% of all the exports of gas in the world.
Ukraine has the 25th largest population in the world. Belarus has the 81st.
Ukraine's economy is the 53rd largest in the world, Belarus's is the 69th (according to the IMF).
In terms of GDP per capita (a reasonable measure of relative prosperity), Belarus ranks 110, Ukraine 120.
How do these countries afford to import so much gas? Are they using it productively?
We should be concerned about Russia using its energy resources to apply political leverage. But with regard to the former Soviet Bloc, is it possible that President Putin has a point when he claims that gas to his neighbours is underpriced?
Mind you, Russia consumes over two-thirds of its own production. That is 15% of total world production, or (if they were importing) over half of all exports, more than the combined imports of the top-five importing nations (USA, Germany, Japan, Italy and Ukraine).
Russia ranks 86th according to GDP per capita, 14th by size of its economy (GDP), and 7th by size of population. Compared to that great guzzler, the USA, it consumes 38% more gas per capita, and nearly six-times more gas relative to the size of its economy. That is no reason for President Putin to subsidise profligacy in the CIS. But he might also want to consider the beam in his own eye. Subsidised energy prices, whether at home or abroad, damage us all.
For the energy geek, many such interesting facts can be found in the International Energy Agency's annual, downloadable factbook Key World Energy Statistics.