President Barack Obama admits US intelligence missed "red flags" before the Christmas Day airliner attack and has demanded immediate reforms to correct them.
Obama said the US security system had failed in a 'potentially disastrous way'.
He said the US had had sufficient information to uncover the plot to blow up a but 'failed to connect the dots'.
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A 23-year-old Nigerian, Umar Farouk Abdulmutallab, allegedly tried to bring down a Northwest Airlines jet over the US city of Detroit on Christmas Day.
Abdulmutallab's father had visited the US embassy in Abuja on November 19 to express fears that radicals might be influencing his son.
Failure to 'connect the dots'
The embassy relayed those concerns the following day in a diplomatic cable to the State Department and the National Counterterrorism Center, which coordinates intelligence among various government agencies.
"The bottom line is this - the US government had sufficient information to have uncovered this plot and potentially disrupt the Christmas Day attack but our intelligence community failed to connect those dots," Obama told reporters in Washington.
"In other words this was not a failure to collect intelligence it was a failure to integrate and understand the intelligence we already had."
US prosecutors charged that Abdulmutallab tried to blow up Flight 253 using a device containing the explosive PETN, also known as pentaerythritol, but was overpowered by passengers.
Allegedly stitched into his underwear, the explosives were not spotted by the traditional metal detectors.
The bomb failed to go off properly, but sparked an on-board fire that was swiftly put out.
The Obama administration has had to fend off criticism of lax safety and intelligence procedures exposed by the foiled bombing attempt.
