The convicted journalists used classified documents in their work on an article about the Signal Intelligence Center.
The documents contained, among other things, secret information about the center's activities, duties, organization, capacity and acquisitions, writes Svenska Yle.
Finland's external security
The series of articles dealt with the Signal Intelligence Centre, an activity about which the Finnish Defense Forces have been very quiet.
According to the prosecutor, the published text contained information that should have been kept secret to protect Finland's external security.
The armed forces state that among the documents used were documents that had the highest possible level of protection.
The prosecutor, who claimed that all the defendants knew that the article contained information that was classified for national security reasons, had requested a 1.5-year suspended sentence for the three defendants.
Denies crime
The journalists have denied any wrongdoing and, according to the defense, did not know that the article contained classified information.
The defense has also stated that it is the newspaper's management, and not the individual journalists and their manager, who are responsible for the publication.
Shortly after the publication, a house search was carried out in one of the reporters' homes, when the police, according to Helsingin Sanomat, seized phones, a computer and USB sticks.
The text is updated.