SPIEGEL: Mr. Gingrich, what can we expect during the first 100 days of the Trump presidency?

Gingrich: You can expect a great deal of action. Donald Trump is a very action-oriented person. I think in the first few weeks, you're going to see a lot of executive orders repealed, peeling back the Obama legacy. You're going to see steps moving forward across a broad range of fronts, and I think they are likely to be very successful opening weeks.

SPIEGEL: Many people fear that after Trump's inauguration on Jan. 20, the United States will become a less tolerant and instead more authoritarian, Putin-style state. This fear is also palpable in Europe.

Gingrich: That is irrational verging on insane. I mean, any suggestion that the most open and diverse society on the planet is likely to in any way resemble Russia requires a suspension of common sense that is pretty hard to deal with. Have you ever been in Moscow?

SPIEGEL: No, unfortunately not.

Gingrich: Then talk to one of your colleagues and ask them what's it like to work there as a journalist, and then just look around here again. You cannot compare those two countries. I know Europe and I know the Europeans. I am an Army brat who lived in Stuttgart and got a Ph.D. in European history, who also lived in France and Belgium. And I am tired of some Europeans saying such things that are baloney.

SPIEGEL: Americans and Europeans fear a new arms race, for example. Trump himself recently said that development might happen.

Gingrich: If you look at how the Russians have worked on their nuclear weapons in the last 10 years, there already is an arms race. Russia is modernizing its nuclear systems. They're moving toward more effective tactical nuclear systems. They're moving toward delivery systems designed to evade anti-ballistic missile defenses. The Russians are investing, by the way, in robotic weapons, including a potential robotic tank. Their investment in new technology, I suspect, outweighs all of the European defense research and development spending combined.

SPIEGEL: Will Donald Trump change the U.S.' relationship with NATO ?

Gingrich: Not dramatically. But I suspect that he's going to be very tough with those countries that don't spend at least 2 percent of their gross domestic product on defense. He will ask them why should we allow a free-ride policy.

SPIEGEL: Does this mean that he will only guarantee the U.S.' full military support to those NATO partner states that fulfill the 2-percent stipulation?

Gingrich: I don't think he can unravel it that way, but I think he will be very direct with any of those states. NATO is an alliance, so all parts of the alliance have to be capable.

SPIEGEL: Europeans fear the consequences of a new Trump-Putin alliance. What do you expect in this regard?

Gingrich: I expect that Trump believes we do not have an obligation to have a Cold War with Russia, but that he is very cautious. By the way, you all have this schizophrenic approach. People are afraid that he'll launch an arms race, and you're afraid that he'll sell out to Putin, and you do both simultaneously. That's pretty cool. I mean, which is the greater fear? Trump is the one who said if somebody really wants an arms race, we'll drown him.

SPIEGEL: The tweet from Trump that triggered this debate could have as much to do with China as Putin.

Gingrich: Well, frankly, on the South China Sea, I suspect we will try to communicate with the Chinese that they are not going to become the leading naval power in our lifetime.

SPIEGEL: Let's talk about Russia again: The American intelligence agencies made a clear assessment about Russian disruptions in the U.S. election campaign. Can Washington tolerate this kind of behavior?

Gingrich: Well, as you know, Obama was even eavesdropping on your chancellor. You know, countries often do such things. I know of nothing the Russians did which had any effect on the American election.

SPIEGEL: The Republican Senators Lindsey Graham and John McCain have a totally different view on the information and have called for a strong American reaction.

Gingrich: I'm a little tired of people who have very big moral positions and very small power in reality. I think the cost for taking on the Russians would be very high. I just want to know how they're going to do it. I don't see that we would do more than make noise. I think Putin has already gotten used to the idea of Obama and his secretary of state, John Kerry, making noise -- it just doesn't seem to impress Moscow at all.

SPIEGEL: Trump frequently mentions his sympathy for Vladimir Putin. Can you describe why Vladimir Putin seems to be so appealing to Donald Trump?

Gingrich: No, not really. I think he thinks of Putin as being a strong person, and I think he thinks of himself as being a very strong person. But I don't think in any way that he thinks of the Putin government as a desirable model.

SPIEGEL: Some Europeans fear Trump could lose his nerve and push the nuclear button.

Gingrich: I think he is very, very cautious about nuclear weapons, and he's seriously concerned. And this might be one of the reasons he wants to deal with Putin carefully, because he's aware of how many nuclear weapons Putin has, and that Russian doctrine is much more open about using nuclear weapons than is American doctrine.

SPIEGEL: Trump may be very careful about Russia, but he can be extremely rough when it comes to other countries, especially Mexico. Do you think he will build the wall -- and that Mexico will really pay for it?

Gingrich: I think the wall will be built, and Mexico will end up paying for it.

SPIEGEL: Mexico's president has repeatedly stated that he won't.

Gingrich: Well, there are a lot of ways to solve it. We could put a fee on all money going into Mexico. We could put a fee on all vehicles coming from Mexico into the United States. We could impound all the money of the Mexican drug cartels (eds: kept in the United States). That by itself will probably pay for it.

SPIEGEL: With the imposition of tariffs and levies, you could start a trade war that would ultimately also harm the U.S.

Gingrich: No. As the largest market on the planet, I'm not particularly worried about countries that want to start a trade war with us. I think they would end up losing.

SPIEGEL: You have said that your biggest fear of a Trump presidency is that his team could lose its nerve. What do you mean exactly?

Gingrich: I mean that there are lots of things that are going to come up to slow them down and stop them: the bureaucracy, the regulations, the lobbyists, the news media. The total weight of everything that tries to stop them from changing things will be so great that there is a danger that the Trump administration will back up and decide to be reasonable. If they decide to become reasonable, they will have failed.

SPIEGEL: What do you mean by that?

Gingrich: Anybody who has looked at Brussels knows what I'm talking about. You know, you try to move the Brussels bureaucracy, and unless you have some capacity to really break it, you can't move it. It just sits there and stares at you. Well, we have the same problem here in the U.S. Remember, most of the bureaucrats voted for Hillary Clinton. Most of the bureaucrats deeply dislike what Trump is trying to accomplish, and most of the bureaucrats think they can't be fired, so they can outlast you.

SPIEGEL: You worked very close with Donald Trump during the campaign. Did he change personally in all those months?

Gingrich: He learned a lot. He's more sobered by the responsibilities. I think that he's more aware of how big the challenge is going to be. I think he's learned a lot about the world. He's talked now, I think, to at least 75 foreign leaders, and I think that he's very concerned about finding the right way to be effective in a responsible way. And he wants to be effective.

SPIEGEL: Several people said that he would become more presidential in office, but this hasn't happened so far.

Gingrich: Donald Trump really is who he is, and I think, for example, he'll probably tweet his entire life -- and that's a fact. I just hope people get over it. Every president developed his own style. You know that we don't recruit them to a certain standard.

SPIEGEL: Does Trump have something like a grand strategy?

Gingrich: No. He has a grand direction. He doesn't have a grand strategy. He wants to re-establish American authority and power and to relaunch the American economy.

SPIEGEL: Do you remember a specific moment when it became clear to you that he really could win this campaign?

Gingrich: Oh yes, very early. There was this debate in August 2015 with the TV anchor Megyn Kelly, and everybody in the elite said he had lost that fight. But people on the internet, by about 60 to 70 percent, said he had won. I thought, If the gap between the elites and the average citizens is that big, something unusual is happening. The country is fed up with political correctness, and it is fed up with government that doesn't work. It's fed up with weakness being interpreted as wisdom. It's pretty straightforward.

SPIEGEL: Who will be the most important adviser during his presidency?

Gingrich: No one. He will have many advisers. He will never allow himself to get to a point where he only has one or two people.

SPIEGEL: You yourself were vetted as a possible running mate and also as a part of Trump's cabinet later. Why are you now staying outside the government?

Gingrich: Because I want to be able to plan strategically out to 2025, and I want to be able to talk without any worry about whatever the party line is. Look, I think this is the most fascinating presidency of my lifetime. I think it has the potential to be very, very good or to be very disappointing, and I'm doing everything I can to make it very good. I don't need a certain job for that. The odds are pretty high he will be successful.