White House spokesman Robert Gibbs says investigators are looking at the system for placing potential terrorists on travel security lists to see if procedures were properly followed and what can be done to make them more effective.
The administration is also investigating aviation detection systems to see how the alleged attacker managed to get on board the Northwest flight in Amsterdam with explosive materials.
No other flights were known to have been targeted. However, Gibbs says federal authorities took precautionary steps "to assume and plan for the very worst."
Gibbs spoke on NBC's "Meet the Press."