WILLIAM BRANGHAM: The Islamic State in Iraq and Syria, known as ISIS, has claimed credit for Friday's terrorist attack in Paris. And the French government also blames the Islamic militant group.

Peter Neumann studies and teaches terrorism and radicalization at King's College in London. He joins me now from there to discuss the group and its intentions.

Peter, these latest attacks sort of put to rest the idea that ISIS was mostly concerned about actions in the Middle East. What do you think that they are trying to accomplish with these most recent attacks?

PETER NEUMANN, Director, International Center for the Study of Radicalization, King's College: I think there are three aims here. The first is classical asymmetric warfare — warfare. You're hitting us. We're going to take revenge by hitting you where it hurts most, namely at home.

The second intention is really to polarize and to divide European societies, to create that sense of Islam against the West, and to create a lot of mess in the countries that they oppose.

The third intention that often gets forgotten is also internally. I think the Islamic State has been on the defensive in its core territory in Iraq and Syria.

And this kind of attack, I think, motivates supporters and gives them again the feeling that they are part of a winning team. And that's really important.

WILLIAM BRANGHAM: So, this is part of their strategy of not just maybe scaring the West off from attacks against them, but trying to recruit more people to the cause?

PETER NEUMANN: Absolutely.

And I think it's really important to understand, in the case of ISIS, that it is important to understand the ideology, but it's also important, for a lot of Western recruits, the sense that they are part of a winning team, that this is a successful, ever-expanding project. That is how it seemed last year.

And it hasn't seemed like that for a number of months. And this kind of attack is almost diverting attention from some of the problems that ISIS is having in Iraq and Syria. And, for — for that reason, it is very important for ISIS to have it.

WILLIAM BRANGHAM: U.S. officials in the past have been saying that the fight against ISIS might take some patience and might take some time.

In your opinion, is this a fight that can be hastened?

PETER NEUMANN: I think it's very dangerous to try to hasten it too much.

I think, contrary to what everyone says, the campaign that has been going on in Iraq and Syria has not been altogether unsuccessful.

It has contained the Islamic State. It has taken away the notion of it as a successful organization in its core territory.

And if you want to hasten it, of course, America can basically bomb the whole place, but the question then becomes, what happens the day after that?

So, you have to bring ISIS down in a way that it actually implodes. That's the only way in which you can have a sustainable end to ISIS.

WILLIAM BRANGHAM: There's obviously been a connection made in the last few days between the refugees coming into Europe and these attacks.

And, obviously, we're torn between a humanitarian disaster going on that is sending all these people into Europe and then fears now people — very real fears of more attacks happening. How do you see that tension playing out?

PETER NEUMANN: It is incredibly dangerous.

The important thing to remember about terrorism is, it is always about — not only about killing people. It's also about creating a political effect.

If the political effect of these attacks is that, in the medium term, European societies are becoming more polarized, that the far right, which is already strong in a lot of countries, is trying to capitalize on that, is trying to merge the refugee issue with the terrorism issue, the effect on European societies could be terrible.

They could even question the idea that people of different faiths, ethnicities can live peacefully together in Europe. So, I do think we are at a fragile moment here in Europe, and we have to be really careful.

WILLIAM BRANGHAM: All right, Peter Neumann of King's College in London, thank you so much for being here.

PETER NEUMANN: Thank you.