RENEE MONTAGNE, host:
U.S. officials say the terror scheme disrupted in London is suggestive of al-Qaida. British authorities arrested 21 people in what they describe as an ongoing investigation. They say that terrorists aimed to blow up a number of flights from the United Kingdom to the U.S. using explosives carried on board in carry-on luggage.
Joining us now to talk about the security situation is John Brennan. He's former head of the National Counterterrorism Center. Good morning.
Mr. JOHN BRENNAN (Former Head of National Counterterrorism Center): Good morning, Renee.
MONTAGNE: U.S. authorities are describing this plot as a sophisticated operation. British officials say the investigation is ongoing. Should Americans be concerned?
Mr. BRENNAN: I think we should be concerned. I think there are two messages, though. One is that I think we should feel very good about the excellent investigative and intelligence work that was able to uncover this plot before it was able to come to fruition, and the British are exceptionally talented in this area in terms of identifying plots as they start to develop.
But secondly, I think it reflects the determination of al-Qaida or other affiliated terrorist organizations to carry out attacks of a devastating nature, directed against the United States - in this case, directed against the United States and the United Kingdom.
MONTAGNE: Can you tell us anything about the nature of cooperation between British and U.S. counterterrorism officials?
Mr. BRENNAN: Well, in fact, I think the relationship between U.S. and British counterterrorism officials is the best in the world. The United States has very, very close relationships with intelligence and security services in the U.K., and there is sharing of information on a regular basis.
Officials are constantly interacting with one another. So this is information that I'm sure was shared over the past several weeks or months, however long the investigation was ongoing, and so it really does reflect, I think, just outstanding work on the part of the British and their interaction with the United States so that we could take the measures here and elevate the threat level in the aviation sector.
MONTAGNE: Well, that elevated threat level, it's up to the highest level possible for flights between the U.S. and the U.K. That's a first since September 11th. What exactly does it mean?
Mr. BRENNAN: Well, it means that this investigation, even though arrests have been made, is still ongoing, and I think U.S. and U.K. authorities want to ensure that they do everything possible to identify possibly additional plotters that may be out there and to ensure that the precautions are in place, particularly now that they have some indication about the type of attack that was going to take place, using liquid or gel with detonators and timers.
And so I think they are doing what is most prudent to do, which is to inspect the - especially the carry-on baggage to make sure that they are able to identify someone else who might be out there that they have not yet been able to detect.
MONTAGNE: Of course we've all been able to carry on hand lotion and gel and all kinds of liquids in hand luggage. It's now been banned on flights between the U.S. and the U.K. Do you think that is an effective measure against this kind of threat, or can the threat be carried out in other ways?
Mr. BRENNAN: Well, you're right. It can be carried out in many ways, but I think what the authorities have to do is go on the intelligence they have about some type of ongoing operational activities and the tactics that may be employed. So I don't think this is going to mean that there will be a diminution of attention paid to other forms of attack, but again, what I think they're most concerned about is that there may be something that has slipped through the net and that may, in fact, be close to operational action.
MONTAGNE: Thank you for talking with us.
Mr. BRENNAN: Thank you, Renee.
MONTAGNE: John Brennan is former head of the National Counterterrorism Center, speaking to us from McLean, Virginia. Transcript provided by NPR, Copyright NPR.