Eurasian Economic Union

The Eurasian Economic Union is an economic union between Armenia, Belarus, Kazakhstan and Russia.  The EEU; not to be confused with the EU, became effective on 1 January 2015.  Kyrgyzstan officially joins in May 2015. 

In 1994, the Kazakh President made a speech in Moscow suggesting the creation of a regional trading block.  This is basically the Eurasian version of the European Union, just with fewer countries and consumers.  The EEU provides a single market of 176 million people.

Russian President Vladimir Putin would like it expanded to all of the post-Soviet republics, except for the Baltics.  Some people think that this is Putin's way of recreating the Soviet Empire.  However, a country can't be a member of both the EU and the EEU.  The Baltic countries of Estonia, Latvia, and Lithuania are all EU members so they won't join the EEU.

Moldova,  Georgia, and Ukraine were all offered EEU membership but all three countries have signed association agreements with the EU instead.  The EU vs. EEU debate is what helped bring down Viktor Yanukovych's government in Ukraine and led to the current problems in Crimea and eastern Ukraine.

It appears that the only real future candidate who may join will be Tajikistan but who knows when that would happen.