Washington DC - US journalist Evan Gershkovich, detained by Russia last year before being exchanged in a prisoner swap, has revealed details about the agency allegedly responsible for his detention.

His first article for the Wall Street Journal since his 16th-month detention scrutinized the little-known Department for Counterintelligence Operations, which he reported is behind "the biggest wave of repression" in the country since the time of Joseph Stalin.

Known as the DKRO, it is responsible for the detention of Gershkovich and other Westerners as part of an operation that has grown dramatically over recent years, according to the report published Thursday by Gershkovich and three colleagues.

After being tasked with securing the release of Russian hit man Vadim Krasikov, jailed in Germany, the DKRO "accelerated a campaign of arresting American citizens," including Gershkovich, to use as "bait."

Russia Officials confirm Russia is hosting deposed Syrian leader Bashar al-Assad

"The more we tugged at this simple question – who in Russia was arresting Americans? – the more we revealed the secret inner machinery that has made it possible for Putin to tighten the screws across Russia's 11 time zones," Gershkovich wrote.

Gershkovich was arrested on espionage charges during a reporting trip in March 2023 and held until a large East-West prisoner swap in August of this year.

His trial was held behind closed doors, and the charges were never substantiated. Gershkovich, the Journal, and the US government denied all accusations of espionage against him.

"I had been arrested and charged as a CIA agent because DKRO had said that's what I was," Gershkovich wrote. "'That's enough for me,' the investigator said."

Krasikov was sent back to Russia as part of the exchange deal.

The article said the shadowy DKRO was a key player in growing Russian repression domestically and is also involved in foreign interference.

Russia Russia's foreign minister threatens to send more "signals" to US in interview with Tucker Carlson

While reporting on the unit, two Journal colleagues "were openly followed through the streets of Vienna and Washington," apparently as an intimidation tactic.

The agency is allegedly headed by Lieutenant General Dmitry Minaev, who Gershkovich said "has a hands-on role in selecting which Americans to arrest, and which Russians to trade them for."