OSLO — The prime minister of Norway acknowledged on Wednesday that his country had fundamentally changed as a result of the attacks on a youth camp and government complex last week, but he vowed to protect the culture of openness that is a source of Norwegian pride.

The attacks have prompted officials to start reassessing Norway’s policy on public security, which seemed defined by a belief that bad things happen elsewhere. Anders Behring Breivik, a self-described Christian crusader who has admitted to the attacks, appeared to face few obstacles when he detonated a car bomb on a busy government plaza last Friday, killing 8 people, then traveled 19 miles and took a ferry to the youth camp on the island of Utoya, where he slaughtered at least 68 people.

“It’s absolutely possible to have an open, democratic, inclusive society, and at the same time have security measures and not be naive,” Prime Minister Jens Stoltenberg told reporters in Oslo. “I think what we have seen is that there is going to be one Norway before and one Norway after July 22,” he said. “But I hope and also believe that the Norway we will see after will be more open, a more tolerant society than what we had before.”