A federal judge in New York has ordered Russian arms dealer Viktor Bout to be removed from solitary confinement, the BBC reported.
Judge Shira Scheindlin said on Friday there was "no rational basis" to believe that Bout posed a threat to other inmates.
His defense argued he had only intended to sell two cargo planes.
Russia questioned the fairness of the verdict and vowed to push for Bout's "return to the motherland."
Judge Scheindlin said that there was no evidence that Bout had connections to terrorists or engaged in violent acts.
The 45-year-old has been held in solitary confinement at the Metropolitan Correctional Center in Manhattan since his extradition from Thailand 15 months ago.
Bout's lawyer, Albert Dayan, had described the condition of his detention as "barbaric."
He said Friday's ruling "recognition that our federal prison system is bound by humane considerations."
Bout is due to sentenced on March 12. He faces a mandatory minimum of 25 years in jail.