Bout, a 55-year-old former Soviet military officer, received his LDPR membership on Monday from Leonid Slutsky, leader of the pro-Kremlin party.

He was serving a 25-year sentence in the United States before he was freed last week in exchange for U.S. basketball star Brittney Griner in a high-level prisoner swap. Bout was sentenced in April 2012 after being convicted of conspiring to kill U.S. citizens and officials, selling millions of dollars of weapons to the Revolutionary Armed Forces of Colombia and aiding a terrorist organization.

“I’m sure that Viktor Bout—a stouthearted and courageous man—will take a rightful place here [at the party]. Welcome to the club,” Slutsky said in a video posted on Telegram. “I want to thank Viktor Anatolievich [Bout] for the decision he has made and welcome him into the ranks of the best political party in today’s Russia,”

The LDPR was founded in 1991 by the late Vladimir Zhirinovsky, who died this past April. It is the third largest party in Russia’s State Duma and secured 7.5 percent of the vote in Russia’s parliamentary elections last year. Slutsky was appointed as the party’s leader in May after Zhirinovsky’s death.

Slutsky said Monday that Bout had spent “long years” in prison in the U.S. but “today he is with us.” He added, “We will return all those who are in trouble outside our motherland.”

The party is seen as loyal to the Kremlin on key issues, including Russian President Vladimir Putin’s decision on February 24 to invade Ukraine.

In his first public interview since his release, Bout took the opportunity to praise the Russian president and the Ukrainian invasion he launched.

“I am proud that I am a Russian person and our president is Putin,” he told Russia’s RT television network. “I know that we will win.”

Yevgeny Prigozhin, an ally of Putin’s and founder of the notorious Wagner Group, a Russian mercenary organization, praised Bout’s move to join the LDPR.

“Viktor Bout is not a person, he is an example of firmness. Bout will certainly be good at the head of any existing party and any movement,” he said in a statement posted by his catering company, Concord.

Meanwhile, Abbas Gallyamov, a political analyst and former speechwriter for Putin, wrote on his Telegram channel: “What prospects can a loser have, especially in Russia, a country obsessed with success?”

“What is Bout famous for? The fact that he traded weapons, blabbed too much to American agents, ended up in prison and waited there until his accomplices swapped him,” Gallyamov said.

Bout has been described by the U.S. Justice Department as one of the most prolific arms dealers in the world.

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