The new information shows that border enforcement officials discovered the suspected extremist ties involving the Nigerian, Umar Farouk Abdulmutallab, in a database despite intelligence failures that have been criticized by President Obama.
"The people in Detroit were prepared to look at him in secondary inspection," a senior law enforcement official said. "The decision had been made. The [database] had picked up the State Department concern about this guy -- that this guy may have been involved with extremist elements in Yemen."
If the intelligence had been detected sooner, it could have resulted in the interrogation and search of Abdulmutallab at the airport in Amsterdam, according to senior law enforcement officials, all of whom requested anonymity because of the sensitivity of the case.
"They could have made the decision on whether to stop him from getting on the plane," the senior law enforcement official said.
But an administration official said late Wednesday that the information would not have resulted in further scrutiny before the suspect departed. Abdulmutallab was in a database containing half a million names of people with suspected extremist links but who are not considered threats. Therefore, border security officials would have sought only to question him upon arrival in the U.S., the administration official said.
Nonetheless, the disclosure shows the complexity of the intelligence and passenger screening systems that are the subject of comprehensive reviews that the administration will release today.
The threshold for requiring a foreign visitor to undergo special scrutiny upon arrival in the U.S. is considerably lower than criteria for stopping a passenger's departure overseas, according to current and former law enforcement officials. That is why border security agencies rely heavily on terrorism watch lists of suspects seen as urgent threats, officials said.
"The public isn't aware how many people are allowed to travel through the U.S., who are linked, who intersect with bad guys or alleged bad guys," a national security official said. "It makes sense from an intelligence perspective. If they are not considered dangerous, it provides intelligence on where they go, who they meet with."
Moreover, the window for identifying a passenger overseas as a potential threat is limited, a senior homeland security official said.
U.S. border enforcement officials have access to passenger data based on lists of those who have made flight reservations. But the in-depth vetting only begins once a comprehensive list, known as a flight manifest, has been generated, just a few hours before takeoff, the homeland security official said.
Customs and Border Protection personnel based at the National Targeting Center in Washington came across the intelligence about Abdulmutallab -- which was based on a tip from the suspect's father to U.S. Embassy officials in Nigeria -- during an in-depth review of the manifest after the plane was en route to Detroit, the other law enforcement officials said.
The administration's review of screening procedures now underway includes an effort to make more information accessible to inspectors further in advance of flights, the senior law enforcement official said. The sheer number of passengers who must be screened and the potential slowdown for air travel posed by more scrutiny remains an impediment, however, officials said.
In contrast, once foreign visitors arrive in the U.S., border inspectors armed with additional screening data can refer them to secondary inspection, which involves more extensive questioning and searches, for reasons including suspected immigration problems or criminal activity.
Customs and Border Protection spokesmen declined to comment because the investigation is still open.
Abdulmutallab, after flying in from Nigeria, boarded the nine-hour flight to Detroit at Schiphol Airport in Amsterdam, one of nine airports around the world where foreign governments permit the presence of U.S. Customs and Border Protection officials in an advisory capacity.
The U.S. border officials work with foreign counterparts and Washington-based American officials to compare passenger lists to law enforcement and intelligence databases. The Americans can ask foreign law enforcement officials to conduct interrogations and searches of passengers who are not U.S. citizens or residents and, in rare instances, question passengers themselves, officials said.
Reservation lists that are generated a few days before flights allow some preliminary screening, officials said. But that information is limited by privacy laws, especially in Europe, and by the vagaries of reporting by airlines, so passenger manifests created with passport information once the flight is closed are a much stronger tool.
Homeland security officials declined to discuss what information reached the U.S. border officials in Amsterdam on Christmas Day or the actions of those officials related to Northwest Airlines Flight 253.