WNBA star Brittney Griner is on her way to San Antonio, Texas, and Russian arms dealer Viktor Bout is back in Moscow after a prisoner exchange Thursday morning in the United Arab Emirates.

From the U.S. perspective, it wasn’t a fair trade: Griner had just started her 9-year sentence at a remote penal colony for possessing of a small amount of hashish oil, while Bout was 11 years into a 25-year sentence for organizing the sale of a hefty arsenal of heavy weapons to a buyers he believed represented Colombia’s FARC rebels. He told undercover U.S. agents he knew the weapons could be used to kill Americans, and he was good with that.

But the Biden administration said this was the only deal on the table. “Over the course of the last few months, the U.S. has offered numerous Russians who are being held here in the U.S., and the Kremlin declined to take the offer,” Margaret Brennan reports at CBS News. “Their top priority was a one-for-one swap, and Viktor Bout himself.”

“There is little doubt that Bout is a top prize for Russian officials,” and they “wanted him home, badly,” The Washington Post reports. “The big question: Why?”

Bout, 55, made his fortune selling arms and fueling bloody conflicts, mostly in Africa, through an air cargo company he started after the fall of the Soviet Union. He is so notorious a figure that a British lawmaker dubbed him the “merchant of death” in 2000 — a nickname that stuck. Hollywood made a movie based roughly on Bout’s life, 2005’s Lord of War starring Nicholas Cage, and a 2014 documentary, The Notorious Mr. Bout. 

The Kremlin maintains that Bout is a legitimate businessman and accuses the U.S. of entrapment. U.S. officials and analysts suggest Russia wanted him back so badly because he has close ties to Russia’s GRU military intelligence service and to Igor Sechin, a close ally of Russian President Vladimir Putin. Bout has denied any such ties, and one theory is he’s now being rewarded for this silence. 

Bout never could have run such a huge smuggling operation without protection and probably cooperation from the Russian government, but he refused to cooperate with U.S. authorities, Harvard’s Simon Saradzhyan tells the Post. “The Russian government is eager to retrieve him so that it stays that way.”

Some Pentagon officials are concerned that Bout will now return to illegally trafficking arms, Politico reports. But the judge who sentenced him to the minimum 25 years back in 2011 says 11 years in prison was ample punishment. “He’s done enough time for what he did in this case,” the retired judge, Shira Scheindlin, told The Associated Press. “He got a hard deal.”