Alex Witt: U.S. counter-terrorism officials say they believe senior al Qaeda leaders including Osama Bin Laden were involved in a plan to strike several European cities in a coordinated assault. Officials say Bin Laden may be trying to show al Qaeda is still strong and able to launch attacks on western targets. Joining me live now, terrorism expert Steve Emerson. Steve, hello, good to see you.

Steve Emerson: Good to see you, Alex.

Alex Witt: So how are U.S. counterterrorism officials making this link between the European threats and Osama Bin Laden?

Steve Emerson: First, there are several things that they've picked up. One is they arrested a man in I think Amsterdam or Germany two days ago who revealed elements of this plot. Number two, there were electronic intelligence intercepts picked up from Pakistan, Afghanistan to Europe. And number three, they had somebody who was part -- would have been part of the plot in Pakistan actually tell U.S. authorities some elements of it. He wasn't read into the whole thing. But altogether, they concluded that a plot was imminent. And as you recall, the Eiffel tower was evacuated. Thousands of extra police were put around Paris, Brussels, parts of Germany. So they took this very seriously. It would have been a Mumbai-style attack, you know when they killed 187 people in Mumbai, right. This would have been an internal attack by radical Muslims inside of Europe because they have no real borders.

Alex Witt: Yeah, I remember that attack happened on Thanksgiving day two years ago because I was on that one. Let's talk about the next question that follows which is do you think that officials have evidence that this type of an attack on these soft targets and tourist areas could also be planned for the U.S.?

Steve Emerson: I think they're very worried. I spoke to a senior intelligence official yesterday. And I said how real is it? One, is there a connection to the U.S.? And two, how real is it? He said, one, it's very real because al Qaeda wants to reassert itself. It's been boasting of being able to carry out an attack for the last nine years like this. And with the exception of Spain and maybe the attacks in Britain in July of '05, they really haven't been able to do much damage or maybe Bali included. But in the U.S., there have been about 139 plots or efforts but no major attack like 9/11. This is really an attempt to re-establish their legitimacy in their own eyes.

Alex Witt: So does it also then say that al Qaeda is understanding it's not capable any more of orchestrating some kind of massive 9/11 style attack? Have they resigned themselves just to be smaller scale attacks?

Steve Emerson: I think, you know, Alex, I think there's sort of like dual strategies. I think that on one level they're trying to do single attacks like they did in the New York's Times Square which was organized by the Taliban last May. Number two, they're thinking about other types of attacks like Mumbai which would kill hundreds. And three, I think they have long-term plans not necessarily are they going to be able to implement them, but to carry out 9/11 style attacks. They're always thinking ahead. We're fighting the last war. That's their advantage.

Alex Witt: Yeah you know Steve you're always listening to the chatter. What are you hearing right now out there?

Steve Emerson: There's a real concern now that something could happen here. There's always concern when you have an imminent plot in Europe and it's being carried out definitively by al Qaeda or an al Qaeda offshoot like the Hakani network like this one. But here I heard that there are actual people in the U.S. who were heard on -- let's just say intercepts that were involved with this plot. I don't know if they'll be arrested, they'll just be watched, but definitely there was a U.S. connection.

Alex Witt: OK, Steve Emerson, always sobering talking to you, but we do appreciate it, nonetheless. Thanks.

Steve Emerson: You bet.