HELSINKI (AP) — Facebook's chief operating officer has apologized to Norwegian Prime Minister Erna Solberg for deleting a photograph from its pages and conceded that "we don't always get it right."

READ MORE: Fat Might Not Be Bad for You After All ]

Sheryl Sandberg said in a letter to Solberg that she'd raised important issues about Facebook's decision to remove postings of an iconic 1972 image of a naked, screaming girl running from a napalm attack in Vietnam. On Friday, following protests in Norway the tech giant reversed its decision and allowed the photo "Terror of War" to be seen on its pages.

In a letter dated Sept. 10, Sandberg conceded that historical importance "sometimes ... outweighs the importance of keeping nudity off Facebook," after Solberg had reposted the 1972 image and other iconic photos with black boxes covering parts of the images.