- Top FSB official Sergei Beseda has been transferred to prison from house arrest, an expert said.
- Beseda is one of several top security officials who've faced punishment over the Ukraine invasion.
- Putin is said to be purging the Kremlin after predictions of an easy victory did not come true.
A senior Russian foreign intelligence official has sent to prison, a respected Russian expert said, after President Vladimir Putin launched a purge of officials blamed for failings in the faltering invasion of Ukraine.
Andrei Soldatov, an leading expert on Russia's security services, tweeted Friday that Sergei Beseda, head of the Fifth Service of the FSB intelligence agency, had been taken to Lefortovo prison.
Lefortovo is a notorious FSB jail on the outskirts of Moscow.
Beseda along with his deputy had been placed under house arrest in March, Soldatov had previously said, as officials from investigated whether moles had buried into Russia's spy agencies and leaked intelligence on Russia's invasion and the planning behind it.
—Andrei Soldatov (@AndreiSoldatov) April 8, 2022
Among Beseda's responsibilities was intelligence and political subversion in former Soviet states, such as Ukraine.
Analysts have blamed Russia's poor performance partly on its failure to anticipate the strength of resistance their forces would face in Ukraine.
Experts said that Russia likely expected to receive support from within Ukraine once it started attacking, which largely failed to materialize.
The jail where he is being detained was during the Soviet era used by the KGB, the forerunner agency of the FSB, to hold political prisoners.
Beseda is not the only official to have faced Putin's anger over failings in the Ukraine invasion.
Roman Gavrilov, the deputy chief of Rosgvardia, the Russian national guard, was fired in March after the force sustained heavy casualties in the initial weeks of the invasion.
Analysts said that deployed national guardsmen, rather than combat-trained soldiers, was another sign that Russia did not expect strong resistance.
Former British military intelligence analyst Phillip Ingram told Insider in March that Putin's punishment of the top officials was a way of sending a message to top commanders that further failures would not be tolerated.