Bush administration officials who did not want to be identified told the newspaper the failures included some reports that cast doubts on whether Pyongyang's uranium enrichment posed an immediate threat and whether the country could actually produce a useful bomb.
Other recent reports said Pyongyang was bluffing a week and a half ago when it announced plans to conduct an underground nuclear test, the newspaper said. Monday, there was a large explosion in North Korea, but it remains unknown if it was atomic or conventional.
The sources said the intelligence community was also caught off guard when North Korea fired its July 4 salvo of seven missiles.
Carl Kropf, a spokesman for Director of National Intelligence John Negroponte, dismissed the allegations of wrong or investigated too late.
"That is absolutely wrong, that we were not tracking this issue for some period of time," Kropf told the newspaper.