It was expected that building up the lists would require additional resources.
The official, who is familiar with the president's strategy, was not authorized to speak publicly and spoke on condition of anonymity.
Obama's remarks Thursday follow a promise earlier in the week to reveal new steps to thwart future terror plots.
No firings over the December security debacle are expected — for now, at least.
In an interview published Thursday by USA Today, national security adviser Gen. James Jones said people who read the report will feel "a certain shock."
Elaborating, Jones said, "The man on the street ... will be surprised that these correlations weren't made" between clues pointing toward a threat from Umar Farouk Abdulmutallab. Even though the 23-year-old Nigerian man was in a database of possible terrorists, he allegedly managed to fly from Nigeria through Amsterdam to Detroit with an explosive concealed on his body.
Homeland Security officials say they had flagged Abdulmutallab as someone who should go through additional security screening upon landing. In a statement early Thursday, the department said the alleged bomber's potential ties to extremists came up in a routine check of passengers en route to the U.S. from overseas. So in short President Obama has earned some of my respect.