The ruling is not final, with a possibility of filing an appeal within 20 days.
The Prosecutor General's Office had asked the court to convict Kusaitė to 10 years in prison for preparations for a terrorist attack.
Prosecutor Mindaugas Dūda said it is a minimum jail term for planning a terrorist attack in a strategic object. In Dūda's words, Kusaitė purchased a book online about production of explosives and later discussed the plan of actions with Chechen siblings from Russia.
The 24-year-old said she got involved in the provocation network of the State Security Department when she was a teenager and was chosen because of her vulnerability.
She was detained at a bus terminal in Lithuania's second-largest city Kaunas in October 2009.