A version of this story appears in CNN’s What Matters newsletter. To get it in your inbox, sign up for free here.

CNN  — 

There’s a growing rift at the top of the Russian government between Vladimir Putin’s official military and the off-the-books mercenary force that has achieved some gains for Russia in Ukraine.

The oligarch figurehead of the private military company Wagner Group, Yevgeny Prigozhin, has been openly critical of Russia’s military and its bureaucracy.

Recruiting for tens of thousands of fighters in Russian jails, Wagner offers freedom and cash after a six-month tour.

Videos of these prison yard pitches made by Prigozhin have been shared on social media, and prison-rights groups in Russia estimate 30,000 have taken up the offer, according to an excellent analysis of what we know about Wagner and Prigozhin by CNN’s Tim Lister. Read Lister’s story.

Brutal tactics for its fighters. A Ukrainian assessment of Wagner tactics suggests the convicts are pushed to the front lines in a human wave. Wagner is using “convicts as cannon fodder to try and storm Ukrainian positions with almost no fire support,” as CNN’s Fred Pleitgen said in a video report he filed after talking to Ukrainian tank operators.

Lister, Pleitgen and CNN’s Victoria Butenko wrote about Wagner’s tactics after seeing the Ukrainian assessment. The focus is on small groups of fighters – a dozen or fewer – guided by drones.

Deserters are said to be shot. The wounded are left behind on battlefields for hours, according to the assessment. Prisoners account for the bulk of Wagner’s casualties as they are pushed to storm Ukrainian positions. More experienced fighters with better equipment follow.

Key lines from their report:

Despite a brutal indifference to casualties – demonstrated by Prigozhin himself – the Ukrainian analysis says that Wagner’s tactics “are the only ones that are effective for the poorly trained mobilized troops that make up the majority of Russian ground forces.”

It suggests the Russian army may even be adapting its tactics to become more like Wagner, saying: “Instead of the classic battalion tactical groups of the Russian Armed Forces, assault units are proposed.” Read more about the Ukrainian assessment.

A former Wagner mercenary said the brutality he witnessed in Ukraine ultimately pushed him to defect, in an exclusive CNN interview on Monday.

Andrei Medvedev spoke with CNN’s Anderson Cooper from Norway’s capital, Oslo, where he is seeking asylum after crossing that country’s Arctic border from Russia.

“They would round up those who did not want to fight and shoot them in front of newcomers,” Medvedev alleged. “They brought two prisoners who refused to go fight and they shot them in front of everyone and buried them right in the trenches that were dug by the trainees.”

Medvedev told CNN that he knew by the sixth day of his deployment in Ukraine that he did not want to return for another tour after witnessing troops being turned into cannon fodder.

He started off with 10 men under his command, a number that grew once prisoners were allowed to join, he said. “There were more dead bodies, and more and more, people coming in. In the end I had a lot of people under my command,” he said. “I couldn’t count how many. They were in constant circulation. Dead bodies, more prisoners, more dead bodies, more prisoners.”

Gaining power over the Russian military. US officials have said Wagner appears to be dueling with Russia’s military for power in the Kremlin.

“In certain instances, Russian military officials are actually subordinate to Wagner’s command,” John Kirby, the strategic communications coordinator at the National Security Council, said late last year. “It’s pretty apparent to us that Wagner is emerging as a rival power center to the Russian military and other Russian ministries.”

Medvedev said Prigozhin is Wagner’s “top leader” but that “everyone knows that it’s subject to the Russian government’s command.”

“Everyone knows that what is happening there is [Putin’s] decision of course,” he added.

CNN’s Natasha Bertrand and Katie Bo Lillis wrote this month that the US assessment is that tensions between the Russian Defense Ministry and Wagner are increasing as Putin relies on Wagner in Ukraine. There are around 50,000 Wagner Group fighters currently deployed to Ukraine, the majority of whom are convicts, according to Kirby.

The US government branded Wagner as a significant transnational criminal organization and imposed new sanctions on Wagner and affiliated groups last week. The US first targeted the organization with sanctions back in 2017.

Growing for years and active in Africa. CNN has been tracking Wagner’s evolution from its founding in 2014 around the Russian invasion of Crimea. In 2019, Lister, Sebastian Shukla and Clarissa Ward published an incredible report uncovering a Wagner Group training ground in the Central African Republic. Wagner has been accused of human rights abuses in Africa and Syria.

Defectors live in fear. People who leave Wagner on the battlefield can be treated with brutality. Video of the murder by sledgehammer of Yevgeny Nuzhin, a Wagner defector who was recaptured by Russians, has caused fear among other fighters.

Medvedev said the public murder of Nuzhin made him “bolder, more determined to leave.”

His daring escape saw him evade arrest “at least 10 times” and dodge bullets from Russian forces, he said. He crossed into Norway over an icy lake using white camouflage to blend in, he said, and relied on the help of human rights activists and even a civilian who provided a passport of someone that looked similar to him.

France-based Russian Vladimir Osechkin has helped people defect who now fear being targeted by Russian spies, who have been known to use poison.

“When the person is in the very high level, they understand very well how the machine of Putin’s regime worked and they have a very good understanding that if they open [up about it], it’s very high risk of the act of terrorism with Novichok or killers,” Osechkin told CNN, referring to poison used in a 2018 attack on former Russian spy Sergei Skripal in Salisbury, England.

Stories of Wagner fighters. The New York Times published a story on Monday about former convicts that joined Wagner and who are now returning home free – and alarming people in their local communities.

Many others do not return. Here’s a CNN report about an African man, Lemekani Nathan Nyirenda, a nuclear engineering student in Moscow sponsored by the Zambian government when he was convicted of unspecified crimes in 2020. Rather than serve his sentence of over nine years, Nyirenda ended up dying as a Wagner mercenary on the front lines in Ukraine in September. Nyirenda was buried in Zambia this month.

CNN’s Jack Forrest, Muhammad Darwish, Katharina Krebs and Tara John contributed to this report.