In the West, he is known as a convicted illicit arms trafficker, “the merchant of death” who helped fuel wars around the world. But in Russia, Viktor Bout was welcomed home this week as something of a hero, or at least an innocent victim of American politics.

The Russian government, its allies and the relentlessly pro-Kremlin media hailed the release of Mr. Bout, 55, by the United States, in exchange for the American basketball star Brittney Griner, and claimed that it meant that President Vladimir V. Putin had bested President Biden.

It was the rare development they could seize on as a victory for Mr. Putin in a war against Ukraine and a showdown with the West that have gone poorly for Russia. And it came after years of Russian news media and officials repeatedly citing Mr. Bout’s case as a monstrous injustice and a major diplomatic irritant.

“Everyone will forget Griner tomorrow,” Yevgeny Popov, co-host of a news show on a state media channel and a member of the Russian Parliament, wrote on the app Telegram on Thursday. “Bout’s life is only beginning.”