Russia's Defense Ministry says it has seen an increase of activity by "Islamic State (IS) units" in countries belonging to the Collective Security Treaty Organization (CSTO).
Deputy Defense Minister Anatoly Antonov said on March 5 that Moscow is "greatly troubled by the situation on the southern frontiers of the CSTO."
He said the "first units" of the IS have appeared on the southern borders of Russian allies, including Tajikistan.
Along with Russia and Tajikistan, the Moscow-based CSTO also includes Armenia, Belarus, Kazakhstan, and Kyrgyzstan.
Because of the situation, Antonov said Russia is "making efforts" to bolster the Russian military bases in Tajikistan and Kyrgyzstan.
Kyrgyzstan's State Committee for National Security said late last month that members from the IS group had penetrated southern Kyrgyzstan and Uzbekistan.
RFE/RL's Kyrgyz Service reported in January that four of six men arrested in the southern city of Osh on suspicion of planning terror acts had trained in Syria, according to officials.