Turkmenistan's state television reports that Akmurad Rejepov, the head of the presidential security service, has been removed from office by presidential decree.
It said Rejepov was being transferred to "another job," which was not specified. Nor was a replacement announced.
"[This could be] an attempt by the present leadership -- namely the president, the defense minister, and the interior minister -- to protect themselves against any surprises from [Akmurad] Rejepov," says regional expert Artem Ulunyan, who is a professor at the Russian Academy of Sciences' Institute of Universal History. "And his transfer [to a different post] could be, not so much a promotion, but in fact a demotion to an insignificant and purely pompous post, as is customary in authoritarian or totalitarian regimes."
Rejepov served the late President Nursultan Niyazov loyally for most of his 21 years in office, during which Niyazov built up a bizarre personality cult and ran the country with unrelenting oppression.
By some accounts, Rejepov's power reached well beyond his official position as head of a 2,000-strong presidential bodyguard service, and he might have been able to influence Niyazov himself.
No explanation for Rejepov's dismissal has been given. But senior regional analyst Svante Cornell, of Sweden's Uppsala University, describes Berdymukhammedov's decision as bold.
"It is definitely a very daring step if the security chief's power is as extensive as has generally been assumed to be the case," Cornell says.
Cornell explains that it is widely thought that Berdymukhammedov was able to take office after Niyazov's death in December because of the backing he received from the security services led by Rejepov, which were the real power behind the throne.
If the new president has now moved against Rejepov, it would be in order to build up his own power base and prevent the security chief from functioning as an alternative power center.
Since becoming president in February, Berdymukhammedov has moved to bring more openness to the secretive style of government to which Turkmenistan's public became accustomed. Cornell says Berdymukhammedov has tried to express both change and continuity.
Among the first things that he did was to distance his government from some of the worst excesses of Niyazov's later rule. But at the same time, he has not moved to dismantle the late leader's personality cult.
"Turkmenistan being a Muslim society, there is a certain need to be respectful of the deceased ruler," Cornell says. "And we must remember that [Soviet leader Nikita] Krushchev's denigration of [Josef] Stalin came only several years after the death of Stalin. So it's going to be a gradual process, but in general we are seeing a visible inclination towards change which is nevertheless going to be very gradual."
There are also mounting indications that Berdymukhammedov will end Turkmenistan's isolation from the outside world, which was a prominent feature of the Niyazov era.
(RFE/RL's Turkmen Service contributed to this report.)