Maria Butina, a Russian national accused of being a spy, is seeking a sentence of time served for the nine months she has spent in jail, according to a new court filing from her lawyers on Friday. Butina, who pleaded guilty in December to a charge of conspiracy to act as an agent of a foreign official, is set to be sentenced on April 26.

In a separate memo filed late Friday, prosecutors said they would be seeking a sentence of 18 months incarceration and deportation. Although they had originally calculated 24 months incarceration, the government has indicated it filed a motion that Butina has provided "substantial assistance" with them by cooperating. Butina appeared before the Senate Intelligence Committee and provided them with "thousands of pages of documents," her lawyers said.

"Butina was not a spy in the traditional sense of trying to gain access to classified information to send back to her home country," the government noted in its filing. "She was not a trained intelligence officer. But the actions she took were nonetheless taken on behalf of the Russian Official for the benefit of the Russian Federation, and those actions had the potential to damage the national security of the United States."

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In a FBI declaration, Robert Anderson Jr, the former assistant director of the FBI's Counterintelligence division, says that he believes that Butina's "spot-and-assess" work on behalf of Russia over two years in the United States was of "tremendous intelligence value." "In my expert opinion, Butina provided the Russian Federation with information that skilled intelligence officers can exploit for years and that may cause significant damage to the United States."

Butina's lawyers wrote in their filing that she had "well-meant intentions" to bridge the relationship between the U.S. and Russia. "She recognizes that her good ends were sought using unlawful means," the filing noted.

Butina's lawyers also detailed her relationship with Alexander Torshin, a deputy governor of the Russian Central Bank. On her visa application, Butina stated she had been previously employed as special assistant, but prosecutors alleged in the charges that she "continued to act under the direction and control of the RUSSIAN OFFICIAL for the purpose of advancing the interests of the Russian Federation after she entered the United States."

Her lawyers noted in the filing that her activities with Torshin "triggered a duty to notify the Attorney General" and "Maria failed to provide the requisite notice. For this, she is remorseful."

Butina pleaded guilty to the statement of offense, which said that early as March 2015 and until 2018, Butina worked with Russian officials to infiltrate and influence U.S. political groups, most notably the National Riffle Association.

The government alleged that Butina had told Russian officials that a candidate in "Party 1" was poised to win the 2016 presidential election and that she had come into contact with a U.S. official who later became a declared presidential candidate. No further details were given in court, however.

As a part of the plea agreement, Butina also acknowledged that she arranged for a delegation to attend the 2017 National Prayer Breakfast.

The case was investigated by the FBI's Washington, D.C. field office, with charges brought by the U.S. attorney's office of the District of Columbia and the National Security Division of the Justice Department. It is not related to special counsel Robert Mueller's Russia probe.

Butina has most recently been held in solitary confinement in a Virginia jail and will remain there until sentencing. A sentencing date has not been set yet because of Butina's ongoing cooperation with the government, but a status hearing has been scheduled for Feb. 12.

Claire Hymes and Robert Legare contributed to this report.