Uzbekistan joined the group - designed to fight international terrorism, drug trafficking and organized crime, and provide military assistance to member states in the event of a military threat - in 1992, but suspended its membership in 1999 along with Georgia and Azerbaijan.

In December 2006, President Islam Karimov moved to restore membership in the organization, which some experts say was designed to prevent NATO’s further eastward expansion and keep former Soviet republics under Russia’s military protection.

Uzbekistan, once the United States’ ally in its military campaign against the Taliban, closed a U.S. base providing support to operations in Afghanistan over criticism of a crackdown by the Uzbek leadership on protests in Andijan in May 2005, when rights groups claimed hundreds of civilians were killed by government troops.

However, Karimov, who has ruled the oil and gas-rich nation since 1989, has recently moved to mend ties with the U.S. and other Western countries by pardoning six jailed human rights activists this year and promising to liberalize the country’s financial system.

The CSTO bloc also includes Armenia, Belarus, Kazakhstan, Russia, and Tajikistan.