“In America, we think that they just drink vodka and want to take over the world,” Mr. Monson said in an interview before the fight in Sukhumi. “But it is America that wrecks countries like Iraq and then just walks away with total impunity.”

Born in Minnesota and raised in Washington State, he said he “grew up rooting for the U.S.A.” But after studying psychology at the University of Illinois and traveling overseas, he says, he “figured out that the world is a little different” from what he had believed. His view of his home country today is summed up by the tattoo on his leg: “Land of Hypocrisy,” it says over an upside-down Stars and Stripes.

Other tattoos include the hammer and sickle, several anarchist emblems, the faces of Marx and Lenin and, on his neck, words that pretty much define his political philosophy, at least with regard to the United States: “Destroy Authority.”

Although he has been a big name in the fighting world since the late 1990s, Mr. Monson did not enter Russia’s pantheon of popular heroes until 2011, when, watched from ringside in Moscow by Vladimir V. Putin, then Russia’s prime minister, he got pummeled by the country’s best-known fighter, Fedor Emelianenko. The Russian shattered his leg and beat his face to a bloody pulp.

Impressed by Mr. Monson’s tenacity in the face of defeat, Mr. Putin telephoned him the next day and told him: “You have the Russian spirit. You never give up.”

After that, Mr. Monson, a father of three, started visiting Russia regularly from his home in Florida, traveling the country for cage fights, including one in St. Petersburg that was also watched by Mr. Putin, a martial arts enthusiast. Mr. Monson now spends much of his time in Russia and in other parts of the former Soviet Union, notably pro-Russian enclaves that crave recognition.