Uzbekistan has suspended its participation in the Russia-dominated Collective Security Treaty Organization, a move that reflects tensions inside the grouping.
CSTO spokesman Vladimir Zainetdinov said the group had received a note from Uzbekistan declaring the suspension of its involvement.
Zainetdinov wouldn't comment on possible motives behind the move. The grouping also includes Russia, Armenia, Belarus, Kazakhstan, Kyrgyzstan and Tajikistan.
Uzbekistan left the grouping once before, in 1999, but returned in 2006.
Vladimir Zharikhin, a Moscow-based political expert, told RIA-Novosti that Uzbekistan's decision had been prompted by President Islam "Karimov's intention to flirt with the U.S."