"This is not a critical inquiry," he said. "We have a lot of respect for the way that our authorities and our different agencies have handled the operations. But we think it's important to go through everything that's happened so that we can learn as much as possible."
Speaking at a news conference on the island of Utoeya, where Anders Breivik slaughtered dozens of young members of his Labor Party Friday, Stoltenberg also announced a national memorial and said the government would help pay for the victims' funerals and compensate their families, the BBC reported.
The people will "not be intimidated or threatened" but will "stand firm in defending our values," the premier vowed.
"The message" is that "we will meet the attacks with more democracy and openness," he said, Views and News from Norway reported.
Stoltenberg also said it was too soon to consider new security laws, but the issue would be addressed, CNN reported.
Despite Breivik's claims he was backed by terrorist cells, domestic intelligence chief Janne Kristiansen told the BBC, "We don't have indications that he has been part of a broader movement or that he has been in connection with other cells or that there are other cells."
Breivik's court-appointed lawyer, Geir Lippestad, said late Tuesday: "He was a little surprised he succeeded -- in his mind 'succeeded.' He was expecting to be stopped earlier by the police or someone else during the actual day. He was surprised that he reached the island."
Breivik, 32, admits making and detonating a large bomb in Oslo Friday that killed at least eight people -- some are still missing -- then shooting and killing at least 68 more, mostly teenagers, at a summer camp run by the Labor Party on Utoeya, 24 miles to the northwest.
The party is the senior partner in the current coalition government.
"He thought he would be killed after the bombing, after the action in the island, and he also thought he would be killed at the trial," Lippestad said. "He believes someone will kill him."
Breivik -- who Lippestad described as a "very cold" man who took drugs before the shootings "to be strong, to be efficient, to keep him awake" -- is convinced he is at the vanguard of a 60-year cultural war and that in war, killing is justified.
It was too early to say whether Breivik would plead not guilty by reason of insanity, Lippestad told reporters, but "this whole case indicated that he is insane -- he has a view of reality that none of the rest of us share."
Lippestad is a member of the Labor Party, which Breivik said he targeted for allegedly letting "cultural Marxism and Muslim domination" creep into Norway and Western Europe. It wasn't clear if Breivik knew Lippestad's party affiliation.
Breivik does not know how many people he killed, Lippestad said, explaining Breivik asked him but he wouldn't tell him.
The high number of the dead prompted prosecutors to consider charging Breivik with crimes against humanity, Oslo police spokeswoman Carol Sandbye said.
Norway's crimes-against-humanity law, conforming with international legal commitments, carries a maximum 30-year sentence, while the two terrorism charges against Breivik carry up to 21 years, Sandbye told The New York Times.
Breivik would be Norway's first person charged under the 2008 law.
Friday's attacks were one of the worst massacres in post-war Europe.
Public reaction swelled Tuesday as people lined up for hours to sign condolence books in the Oslo University assembly hall. They covered Oslo streets with roses and blanketed the sidewalk in front of Oslo Cathedral, the city's most important church, with flowers and candles.
In addition, more than 6,000 people "liked," signed their names and posted supportive messages of oneness on a Facebook page titled "If one man can show that much hate, think of how much love we can show."
"Norway is writing a new cultural story," Claudia Christine Pieper of Hamburg, Germany, wrote. "Thanks for showing the way and inspiring us about another way of responding to cruelty."
Norwegian Foreign Minister Jonas Gahr Store went to a large Oslo mosque of the Sunni Muslim World Islamic Mission Tuesday evening to express solidarity with the country's Muslim population.
He told the Times Breivik's victims on the island were "Christians, Muslims, atheists -- they were everything."