In the plea hearing, she said she wanted to wait until the court ruled on whether she must pay for her own lawyer or whether she will get financial help.
In her statements to the media, Hartmann has accused the United Nations war crimes tribunal of "trying to silence the truth".
In her book, she says that the prosecution at the ICTY was allegedly unhappy with the tribunal's decision to accept a Serbian request that some portions of its state archive be considered in closed sessions.
Hartmann believes that it was these pieces of evidence that were key in determining Serbia's responsibility for the genocide in Bosnia in 1992.
The prosecution, according to Hartmann, could not discuss this publicly because the judges allegedly protected themselves by making their decisions confidential.
The Hague believes that Hartmann knew she was engaging in a violation and had intended to obstruct justice.
Hartmann considers that she had the right to publish the information she obtained, and told Serbian media shortly after the indictment against her was issued that she "did not breach confidentiality of information".
If she is convicted, she faces a maximum sentence of seven years' imprisonment and a maximum fine of $126,000.