An unusual federal trial detailing the inner workings of a Russian influence operation in the United States ended on Thursday with jurors convicting four members of Black power groups of conspiring to act as agents of the Russian government. The defendants were acquitted of failing to register as Russian agents, a more serious charge.

Prosecutors had argued during the weeklong trial in Tampa that the defendants had engaged in a seven-year conspiracy to sow division in American politics. The defendants countered that the government was trying to criminalize their support of Russian ideology, which they argued was protected political speech.

Speaking after the verdict on Thursday, three of the defendants and their lawyers said they considered the acquittal on the more serious charge a victory. They also vowed to appeal the conviction on the lesser charges.

“The most important thing is they were unable to convict us of working for anybody except Black people,” Omali Yeshitela, the chairman of the Uhuru Movement, said on the courthouse steps, according to The Tampa Bay Times. “I am willing to be charged and found guilty of working for Black people.”

The Uhuru Movement is the activist arm of the African People’s Socialist Party, an organization promoting Black power. The groups are based in St. Petersburg, Fla., and St. Louis; for decades, the Uhuru Movement has protested issues like racism, colonialism and policing.

At trial, prosecutors laid out how Mr. Yeshitela visited Moscow and established a long-term relationship with a Russian man who worked with the F.S.B., a Russian intelligence agency. From 2015 to 2022, prosecutors said, Russians directed and in some cases paid the Americans to push Russian propaganda.

The other defendants are Penny Joanne Hess, an Uhuru Movement leader; Jesse Nevel, an Uhuru Movement member; and Augustus C. Romain Jr., a former African People’s Socialist Party member and founder of Black Hammer, a radical Black separatist organization in Atlanta. Mr. Romain mostly represented himself at trial.

The trial, which had been scheduled to last for about four weeks, concluded more quickly than expected. The conspiracy conviction carries a maximum sentence of five years in prison. No sentencing date has been set.