Uzbekistan withdrew from a defence alliance between Russia and former six former Soviet satellite states - Collective Security Treaty Organisation (CTSO) - on Monday.
The Uzbek Foreign Ministry said the decision stemmed from their opposition to recent attempts to strengthen military cooperation within the CTSO.
Russia remains sceptical, and believes the withdrawal paves the way for a us base in uzbekistan preceding the NATO pullout of Afghanistan.
In 1999 Uzbekistan pulled out of the CTSO, allowing the US to use its air base in the south during the Afghan war (2001-2005). In 2006, it was accepted back into the CTSO, after the president ordered US forces to leave after the Americans criticised the Uzbek troops for the killing of civilians in Andijan.
The CSTO also includes Russia, Armenia, Belarus, Kazakhstan, Kyrgyzstan and Tajikistan.
