The main trial is expected to begin on May 26, according to Attunda District Court.
Landerholm, who left his post as national security adviser when the criminal investigation against him began in January this year, was charged on Tuesday for gross negligence with confidential information.
According to the indictment, he "through gross negligence, unauthorizedly disclosed" confidential information in documents that he forgot at a conference center outside Stockholm in March 2023.
The information that is considered to have been disclosed through Landerholm's actions concerns, according to the indictment, "matters of a secret nature" whose disclosure to a foreign power could harm Sweden's security.
Landerholm denies any wrongdoing.
"He even questions whether what he is accused of is criminalized," wrote his lawyer Johan Eriksson in a written comment to TT on Tuesday.
Six people are called to testify in the trial, three from the Government Offices and three from Gällöfsta Conference and Manor, where the documents in question were forgotten.
