Russia is in talks with Tajikistan to send up to 3,000 border guards to the country to protect its border with Afghanistan against militants and drug smugglers, said security sources and analysts.
Russia fears the planned withdrawal of NATO troops from Afghanistan by 2014 will create a power vacuum allowing Islamist militants fighting U.S. forces there to move into Central Asia.
Moscow, Beijing and Washington are vying for influence in the region.
"There are negotiations ongoing with Russia," said a high-ranking border security source in Tajikistan, referring to talks about border guards.
Twenty years after the fall of the Soviet Union, Moscow sees Central Asia as part of its sphere of interest and worries that an upsurge in Islamist violence or heroin trafficking could upset the predominantly Muslim, oil- and gas-producing region.
Moscow wants to clamp down on the region, which has served for centuries as a major drug-trafficking route. Moscow's anti-drug tsar Viktor Ivanov says up to a quarter of all Afghan heroin reaches Russia, coming through Central Asia.
Russia is the world's largest per capita heroin consumer and is struggling to contain a potentially crippling heroin crisis, with at least 2 million addicts, Western health officials say.
"Russia fears the weakness of Tajikistan forces when the U.S. pulls its troops out of Afghanistan. They expect that a large number of Islamist extremists and drug traders will penetrate Tajikistan's borders and enter Central Asia," said regional expert Vyacheslav Tseluiko from Ukraine's University of Kharkiv.
Russia says heroin is smuggled out of Afghanistan through the porous border with impoverished Tajikistan, then via Kyrgyzstan and Kazakhstan and onto the Russian market.
"Right now talks are ongoing between Russia and Tajikistan regarding the issue of raising the number of border guard troops to 2,000 soldiers," said independent analyst Adil Mukashev, who is based in Almaty, Kazakhstan.
"There has already been a preliminary agreement, and the talks are expected to be completed by July," he said, citing several sources in Russian security organizations.
A U.S.-based security analyst, citing Russian and Tajik sources, said Russia was effectively taking over border control by sending 3,000 border guards to train and manage Tajik forces.
Russian border guard troops withdrew from Tajikistan in 2005, ending a Soviet-era legacy, though Moscow still has between 5,000 and 6,000 military troops in its military base on Tajikistan's western border.
The Border Guard Service did not answer repeated requests for comment.