Anders Breivik is currently in court and has five days to explain his actions. The 33-year-old has pleaded not guilty to the massacre last July.
Breivik believes he was protecting Norway from Muslims by attacking the left-leaning political party he blames for the country's liberal immigration policies.
"The attacks on July 22 were a preventive strike. I acted in self-defense on behalf of my people, my city, my country," Breivik told the court.
So far he has demanded to be found innocent of terror and murder charges. The court must make a decision on Breivik's sanity.
The Associated Press contributed to this report.