The woman is accused of raising funds that benefitted the Ukrainian armed forces.
The Federal Security Service (FSB) in the city of Yekaterinburg took into custody the unnamed woman, identified only as a 33-year-old resident of Los Angeles, state media reported on Tuesday.
She “was involved in providing financial assistance to a foreign state in activities directed against the security of our country”, said a statement by the security agency carried by Russian media.
It said since February 2022, she was “proactively collecting money” for a Ukrainian organisation that would ultimately benefit the Ukrainian armed forces in the form of purchase of “tactical medicine items, equipment, weapons and ammunition”.
The woman had also allegedly taken part in multiple public demonstrations in the US in support of Ukraine, which is financially and militarily backed by a Western coalition after Russia invaded it in February 2022.
Russian state media released a video as well, which showed hooded FSB officers escorting and handcuffing a woman in a white coat and a white hat pulled down over her eyes.
Treason is punishable by up to 20 years in prison in Russia.
The Wall Street Journal reporter, Evan Gershkovich, is one of several US nationals who are currently imprisoned in Russia. The journalist was arrested last year on charges of espionage that have been rejected by Gershkovich, the US outlet and the US government.
Russian-American journalist Alsu Kurmasheva has been in prison since October and charged with failing to register as a “foreign agent” and spreading “false information” about Russia’s military campaign in Ukraine.
Paul Whelan, a former US marine and security executive, was arrested in Russia in 2018 and convicted of spying in 2020.
Russian President Vladimir Putin said this month that Moscow is open to a prisoner swap for Gershkovich as a “gesture of goodwill”.
Russia and Ukraine have also completed several rounds of prisoner exchanges in the past few months, with 100 prisoners of war exchanged earlier this month.