The United States and Russia carried out a historic prisoner exchange on Thursday, under which, two dozen detainees, including former US Marine Paul Whelan and Wall Street Journal reporter Evan Gershkovich, are being released.
The woman, a resident of Los Angeles, was detained for allegedly providing financial assistance to a Ukrainian organisation involved in activities deemed detrimental to Russia's security.
National Security Council spokesman John Kirby said, "We're working hard to see what we can do to get another proposal that might be more successful." This comes after the Kremlin rejected a previous proposal.