Russian citizen Maria Butina, sentenced to 18 months behind bars on Friday for violating the US law on foreign agents, may be released in November, her attorney Robert Driscoll told reporters after the sentencing.

"We expect that Maria should be back to Russia hopefully in the full some time, maybe in November," he said.

According to Driscoll, the defense team would look into the possibility of filing an appeal, but sees little potential for it due to the plea bargain that Butina signed last December.

"We disagree strongly with the court sentence," he said, adding that Butina "plead guilty in this case and, therefore, accepts the sentence."

Earlier on Friday, a court in Washington sustained the prosecution’s request for sentencing Butina to 18 months behind bars for violating the US law on the registration of foreign agents. Judge Tanya Chutkan ignored the defense lawyers’ request that Butina should be sentenced to a term equal to the period she had already spent in custody, which is nine months.

"I feel terrible for Maria’s family. <...> I wish we have done more to get her out sooner. <...> I do not believe an additional nine months in jail serves any purpose in terms of punishment or contrition at this point, <...> so I don’t think that was necessary" he added.

Maria Butina, 30, was arrested in Washington DC on July 15, right before the Helsinki meeting between Russian President Vladimir Putin and his US counterpart Donald Trump. The US Department of Justice said that she was suspected of acting "as an agent of Russia inside the United States by developing relationships with US persons and infiltrating organizations having influence in American politics, for the purpose of advancing the interests of the Russian Federation."

On December 13, Butina pleaded guilty to a conspiracy to violate the US law governing foreign agents operating in the country and signed a plea agreement. The prosecution said at the time that the process of Butina’s cooperation with the investigation might take some time.

Butina had arrived in the United States for a course of studies. Last spring she obtained a master’s degree at American University, where she studied international relations.