SPIEGEL: Mr. Secretary, why do you need to know how European citizens traveling to the United States pay for their tickets or whether they fly in business class or economy or if they have special meal requests?

Chertoff: If we had had a program prior to Sept. 11 where we were able to get information about how everybody paid for a ticket -- including a contact telephone number and a seat number -- we would have been able within a matter of moments to identify 11 of the 19 hijackers who came into the United States. It was by finding that information after the attacks that we were able to track their pattern of behavior and also identify others who had been part of the plot.

SPIEGEL: So you really believe that the "Passenger Name Record," the 34 different types of data you get from every traveler coming from Europe, could help to prevent a new terrorist attack?

Chertoff: Imagine that our troops in Afghanistan raided an al-Qaida safe house and captured a computer containing the cell phone numbers of operatives in Europe. Wouldn't it be important to know whether one of those cell phone numbers was used to book a trans-Atlantic flight? That, in a nutshell, is why we need the data, so that we could for example identify a connection between someone on a flight and someone who we know to be a terrorist.

SPIEGEL: The agreement to deliver this kind of data will end on July 31, and many European countries and the European Union want to drastically reduce the amount of information that is provided to the US. Do you see any chance for a compromise?

Chertoff: I prefer to think that we will find a solution. In the end, I think Europeans have to recognize we can never be put in a position where we surrender to another government the determination of who comes into our country.

SPIEGEL: You are very optimistic that Europe will accept your conditions.

Chertoff: I want to turn the question around. If we were to stop doing what we are doing because the Europeans object and then someone came in and we had another Sept. 11 and I were to have to say: "Well, we surrendered our information because the European authorities didn't want us to use it." What would the American public say? What would the surviving family members say? "You caused my relative to die?" And then, what would the European privacy authorities say? "We're sorry? It's too bad, this is the price you pay?"

SPIEGEL: But the European countries fear that every person traveling will be treated like a suspect.

Chertoff: We don't necessarily want to increase the amount of data. But we want to make sure that we can continue to share it within the government, so that we can analyze it. And we want to be able to retain it sufficiently long that we can identify plots that may in many cases be years, if not decades, in the making.

SPIEGEL: That's exactly the concern -- that data of millions and millions of Europeans could be held in the computers of your intelligence agencies for decades.

Chertoff: Currently, we keep it for 40 years, I don't know if we will need it that long. Certainly looking back on plots historically, we have seen information well over 10 years and maybe up to 15 or 20 years old being relevant in determining connections and plots. So we are talking about a time frame that is sufficient to allow us to make connections that may not be immediately apparent.

SPIEGEL: It seems obvious that you fear that terrorists executing a possible future attack in the United States will come from Europe. Why?

Chertoff: Because we are seeing increasingly activity, recruitment of Europeans or people who have European papers to carry out terrorist plots. We look at July 2005 in London, we look at August 2006, the airline plot that was aborted through good intelligence work, we look at the failed rail plot in Germany. It seems that either homegrown or al-Qaida-directed activity is occurring in Europe. And when we look at what our vulnerabilities are, we recognize that the visa waiver program, which eliminates the visa process, creates a vulnerability.

SPIEGEL: The fear in the US administration seems so widespread that you don't even want to rely solely on the passenger data. In addition you endorse a sort of online registration every European would have to fill out 48 hours before traveling.

Chertoff: We proposed to Congress a way that would loosen the visa waiver process and make it more flexible in some respects -- so that countries in Eastern Europe could participate. But at the same time we want to elevate the security level generally by having what we call an "electronic travel authorization."

SPIEGEL: What would this look like?

Chertoff: It would be similar to what they do in Australia where visa waiver travelers would register online in advance, and they would, therefore, know before they arrive in the United States whether there was going to be a problem with their being admitted. Currently, because we don't necessarily know who is coming until right before they leave, it is often the case that someone travels six or eight hours across the Atlantic, that person arrives, and we say: "Guess what, we are not admitting you."

SPIEGEL: So it will mean that every European citizen has to fill out such a form two days before traveling?

Chertoff: Right. The registration would have a shelf life of some years. It wouldn't be something you do every trip, you would do it periodically.

SPIEGEL: To make this point clear -- you would only be allowed to travel with this kind of pre-clearance?

Chertoff: Yes. How much better for them and for us if we can address issues up front, and then, if something needs to be resolved with an interview, we can tell the person to go to the consular-officer in the embassy.

SPIEGEL: It will be the end of any kind of last-minute travellers.

Chertoff: I am sure that when we put the regulations out, there will be some provision for people who have a short-notice need for expedited processing. We shouldn't let the unusal or exceptional case prevent us from dealing with the majority of cases.

SPIEGEL: So if you screen "every guest in your house" as you phrased it, will American citizens who travel to Europe undergo similar treatment?

Chertoff: Absolutely. It ought to be reciprocal. We are perfectly content to have Europe impose the same basic approach. I think that is fair.

SPIEGEL: Are you not concerned that you will be accused of turning the United States into a kind of fortress?

Chertoff: No. What we are trying to do is avoid a fortress. We are not suggesting to bring back the visa system for Europe, although frankly you will find some people in the US who argue we should do that. The problem is if you don't do anything about this and then, God forbid, someone comes from Europe and commits a terrorist act, then I am unfortunately confident that there would be a very strong reaction in the opposite direction. What you would see is an outcry at the visa waiver program. That's why everybody needs to be interviewed. Its better investing a little bit in advance to increase security than to wait until a disaster happens. Then you would see perhaps an over-reaction that would cause some serious damage to trade and travel.

SPIEGEL: Resistance in Europe has also increased as a result of the diminished trust in the American system caused here by the way Washington fought the "war on terror."

Chertoff: I am not saying that everything the US has done has been flawless. Clearly, we have done things, particularly in the heat of the battle, that now have been recalibrated. But we have to remember who the real enemy is. People who amplify the differences and make more of them than there are, maybe for political reasons, are not doing Europe and the US a service.

SPIEGEL: You recently visited the European Parliament and had a chance to listen, first hand, to just how strong this criticism has become.

Chertoff: I suggest to your readers that they take a look at the world of 2007. We have the Taliban trying to regain ground in Afghanistan. If they should succeed in controlling a province, what do Europeans think would happen? Even if you take Iraq out of the picture, you see struggles with extreme Islamist groups trying to take control of Somalia. We see bombs in Algeria and Morocco. Al-Qaida and terror groups in the Maghreb now forging a union. That is all happening at the doorstep of Europe.

SPIEGEL: You don't think Europe is taking the threat seriously enough?

Chertoff: The railway plot in Germany didn't succeed, but what would have happened if it had? What if it were 10 trains? What if it was an airplane? What would be the point at which Europeans would suddenly say, you know, this is not just a tolerable level of terrorism, but this is really a threat to society?

SPIEGEL: You believe Muslims in Europe tend to be more susceptible to radical Islam?

Chertoff: We worry about this in the United States as well, but we haven't seen the phenomenon quite so advanced here as in Europe. I certainly worry about European extremists getting in airplanes and coming to the US. We don't want to totally rely upon the fact that a foreign government is going to know that one of their citizens is suspicious and is going to be coming here.

SPIEGEL: You recently talked about Muslims in Europe being treated like second-class-citizens and suggested that that might have to do with a colonial legacy.

Chertoff: I think in this country, people who have been admitted as immigrants tend to assimilate better than Muslim communities in general. They seem to be more prosperous and better educated than even the average American. So they are well integrated. It is not a guarantee, but it is certainly a positive thing. I raise the question whether in some cases in Europe some of the immigration took place as a consequence of colonial relationships that allowed people to emigrate, but they didn't neccessarily feel that they are integrated into society.

SPIEGEL: You make it pretty clear that you don't want to hear any more criticism from Europe.

Chertoff: No. You are perfectly free to criticize us, and we to criticize you. What is not useful is a tone of moral superiority, for people to act as if they are sitting in moral judgement of another country. That ought to be reserved only for those countries that are so clearly beyond the pale that it is clear that they are really doing something impermissible. I think it is an exercise in moral confusion to treat differences in opinion on peripheral matters between the US and Europe as being a kind of moral problem.

Interview conducted by Georg Mascolo