RACHEL MARTIN, HOST:
Investigators in the U.K. still have a lot of questions. They're trying to figure out whether or not the suicide bomber who killed 22 people in Manchester had help. ISIS has claimed responsibility for the attack, so was the bomber directly connected to a terror network or just inspired by them to carry out an attack?
To discuss the U.K.'s counterterrorism strategy, let's bring in Peter Neumann of King's College London. He joins us on the line from Vienna. Thanks so much for being with us.
PETER NEUMANN: Thank you.
MARTIN: Peter, does anything about the incident in Manchester indicate a wider group was involved?
NEUMANN: I think there are some pointers. And in fact, the British home secretary just said that she believes that the attacker did not act on his own. Two indicators in particular, number one, the number of arrests that have been made over the past 24 hours by British police, assumed associates of the attacker, and second, the relative sophistication of the attack.
It is not so easy for many of these wannabe terrorists to build a functioning explosive device. Most of them, in fact, fail doing so and have given up. The fact that he had a functioning explosive device seems to indicate a degree - at least a degree of sophistication.
MARTIN: ISIS has called the suicide bomber a, quote, "soldier of the caliphate." What does that reveal? What does that signify?
NEUMANN: Not so much at this point. We know that ISIS not only claims attacks that are carried out by sworn members, it also claims attacks by people who were merely inspired. What I think is far more important is what has emerged, which is that according to the French and British interior ministers, this person has traveled to Syria and was a so-called foreign fighter who has returned to Western Europe. And if that turns out to be confirmed, then that would be a huge game-changer for the whole conversation about how to deal with these people in Europe.
MARTIN: Apparently, the assailant was known to British security services. Does that worry you? I mean, does the U.K. have a good track record when it comes to foiling threats like this?
NEUMANN: Yes, it does. And I think it is important to keep in mind that the British system of counterterrorism is a pretty good one. And on average, the British have foiled one major terrorist attack every year. But like every European service, the British have had a capacity problem.
The number of people that have turned up on their radar screen in recent years has been so large that even a very sophisticated system like the British one has struggled. And the more - the more cases you have, the more difficult the judgment calls become. Who do you watch? Who do you consider to be acutely dangerous? And so that's been really difficult. And mistakes happen in those cases.
MARTIN: Peter Neumann of the International Center for the Study of Radicalization and Political Violence at King's College. Peter, thanks so much for your time this morning.
NEUMANN: Thank you, Rachel. Transcript provided by NPR, Copyright NPR.