America treated the Oslo attacks as a fringe incident. Here's why that's been so dangerous.

Ten years ago Thursday, a white supremacist terrorist disguised himself as a police officer and brutally murdered 77 people — most of whom were children and young adults — in Norway. But it has been only a year since governments have turned their focus to white supremacy as a rising cause of violence.

It has been only a year since governments have turned their focus to white supremacy as a rising cause of violence.

The attacks marked the...