DER SPIEGEL: Mr. President, you first met Vladimir Putin in person almost 10 years ago. What was your impression of him?

Niinistö: It was in June 2012 at the St. Petersburg Economic Forum. Putin hosted a dinner, and after that, we drove to Karelia, to a village with summer cottages, and played ice hockey. At some point, he asked me: Why is Finland so enthusiastic about becoming a NATO member?

DER SPIEGEL: What was your answer?

Niinistö: That our government at that time, while it didn't rule out NATO membership in its platforms, was not initiating preparations for accession during its term in office. I told him that Finland wants to deepen relations with its neighbors in Sweden and Norway, as well as with the United States and the countries of the European Union and to enhance its partnership with NATO, and that I am an advocate for strengthening European defense. He asked me why. I said because every independent nation strives to maximize its security. That was the end of the discussion.

DER SPIEGEL: Can the man you met back then be compared with today’s Putin?

Niinistö: I would not say I have noticed any major change. Just one thing, perhaps: He sounds more decisive. And there was a very interesting development last year. Would you like me to break it down for you? From my personal perspective?

DER SPIEGEL: Sure.

Niinistö: I remember last spring, when more Russian troops were already being concentrated near the Ukrainian border, very well. In April, I had a telephone conversation with Putin and he told me it was just a military exercise and that the troops would be withdrawn in 10 days. A short time before, he had spoken with U.S. President Joe Biden, and it seemed to me there was a connection between the phone call and the announcement of the pullout. And the troops really did withdraw.

DER SPIEGEL: When did you first sense signs of the escalation that would follow?

Niinistö: In June, Biden and Putin met for a summit in Geneva to discuss arms control, after which the signals coming from both sides were positive. It was at the time when Biden was traveling through Europe. It became clear to us and other European countries that the Biden administration no longer sees Russia as its primary global adversary, but rather China. At the same time, we talked in different formats about security on the Continent, in the NATO countries and in the EU as well. In August, I asked Putin what he thought of this security debate. He didn’t answer. Then, in mid-October, I heard the first warning signals from Washington and Moscow that there might be problems.

DER SPIEGEL: Have you asked Putin about this?

Niinistö: At the end of October, I was a guest at the Kremlin and I asked him if there were any difficulties in the negotiations with the U.S.

DER SPIEGEL: That was one day before the Washington Post reported on the new troop deployments near the Ukrainian border.

Niinistö: Yes, but I wasn't fully aware of that at the time. Putin answered my question by saying: No, everything is OK. A short time later, CIA chief William Burns flew to Moscow, and we all knew that something wasn’t quite right. You asked me if Putin has changed. I don't see a change in himself as a leader. But I do see a change in his behavior. Suddenly, he started to behave in a very, very decisive way. I think he saw an opportunity and wanted to use the moment to take everything he had already had in his mind for years. Sometimes, I guess you have to read him even when he doesn't answer.

DER SPIEGEL: How do you explain the drastic change in Putin’s behavior between the summer and autumn of last year?

Niinistö: It's difficult to define. There certainly wasn’t a specific incident that would have totally changed the picture from the Russian point of view. But we did talk extensively in Europe last year about security on the Continent, and perhaps Moscow felt it was not involved, or would have wanted to be the master of that game.

DER SPIEGEL: In mid-December, Putin presented the West with a list of demands, including that NATO essentially pull back to its 1997 borders, that it pledge to cease eastward expansion and that it end military activities in both Ukraine and Eastern Europe. But Moscow must know that neither NATO nor Europe nor the U.S. would make such commitments. Is Putin serious about these demands?

Niinistö: I was surprised myself when I saw them for the first time. It had to be clear even to those who issued the demands that they were almost impossible to fulfill. I spoke to Putin by phone on Dec. 14, and the parts of our discussion about his demands were very formal. I even thought that he was reading from a piece of paper. He just wanted to repeat the demands – nothing else.

DER SPIEGEL: What do you think Moscow is aiming at?

Niinistö: It’s totally impossible for me to guess what Putin wants. In December, I wrote the following in my journal: At first, I thought that Ukraine is just the bait for the Kremlin, and the catch is on the general demands towards the U.S. and NATO. But maybe, in the end, Russia also wants to eat the bait. I now think it may have more to do with Ukraine. I think the implementation of the Minsk agreement is a key issue for Russia. We now see that (French) President Macron is very active in the Normandy process and is looking for solutions.

DER SPIEGEL: Russia negotiated the Minsk agreement in 2015 together with Germany, France and Ukraine - during a period of weakness in Ukraine. Many Ukrainians view the treaty, which was never fully implemented, as a victory for Putin. Why have you changed your assessment as far as Russia’s priorities are concerned?

Niinistö: On Jan. 21, I spoke with Putin on the phone for more than an hour. He mentioned the Minsk agreement. I didn’t say anything about it. But the Kremlin’s press release about the phone call stated that both presidents had pointed out the importance of the agreement. That was OK for me because I have been emphasizing that for seven years. But the press release from the Russian Foreign Ministry about our phone call only mentioned the Minsk part of our discussion and nothing else. That made me think.

DER SPIEGEL: Do you think it is clear to Putin how high the price and how tough the sanctions will be if Russian troops invade Ukraine? Not to mention the fact that the West may be even more united in the event of an invasion?

Niinistö: Of course, I don't know what Putin thinks. But Russia is willing to pay high prices for what it considers to be important. The sanctions will certainly have a major impact on the Russian economy, particularly in the long term.

DER SPIEGEL: Within the EU, you have the reputation of being the leader who knows and understands Putin the best.

Niinistö: I’m not sure how well I understand him. But I try to. Just as we all try to.

DER SPIEGEL: There has been sharp criticism of the government in Berlin for inaction in the current crisis. Do you see it that way as well?

Niinistö: I see that your chancellor has taken action. He was in Washington and he’s traveling to Kyiv and Moscow, I think that is very positive.

DER SPIEGEL: And yet the Germans are reluctant to put the operation of the Nord Stream 2  pipeline on the table when it comes to sanctions.

Niinistö: There were just initial talks in Washington between Scholz and Biden. I don’t know what the exact German position is at the moment. In any case, Joe Biden has said that a Russian attack on Ukraine would be the end of Nord Stream 2.

DER SPIEGEL: Finland shares a 1,340-kilometer (833-mile) border with Russia. Does that fact mean that you see the current crisis differently than the rest of Europe does?

Niinistö: I was disappointed and surprised by Brussels after the list of demands from Moscow was on the table. If you have a union and then someone comes from the outside and makes demands that may be directed at the U.S., but concern some countries inside the union, then there should be a reaction coming from your backbone. If someone is walking across your property, you would also react. But I’m missing this reflex. I didn't even see this kind of reaction in December from the European Parliament, which usually reacts to everything bad that happens in the world. I found that embarrassing. This disappointment sits deeper in my mind and heart than I could express.

DER SPIEGEL: Finland just decided to order 64 highly modern new F-35 fighter jets for $9 billion. That definitely makes it seem like you feel threatened by Russia.

Niinistö: I have always emphasized: The most important thing is that we are militarily capable of showing: If somebody wants to come to us uninvited, it will be very expensive. And also, if something really crucial takes place, you will be a lucrative partner if you are strong. In Finland, we have close to 300,000 trained reservists we can mobilize. I don’t think Germany has that many. Finland has one of the strongest artilleries in Europe.

DER SPIEGEL: In the debate about Russia’s relationship with Ukraine, the term "Finlandization" has recently re-emerged. Much as the Soviet Union didn’t allow Finland to join the Western alliance after World War II, some in Moscow are now demanding that Ukraine should officially become neutral. How do you react to that historical analogy?

Niinistö: I don't understand why people would mix that up with the Ukrainian situation. In Finland, "Finlandization" has a very negative sound. It is reminiscent of the 1970s, when many Finnish politicians thought that you upgrade yourself by being very polite and understanding to the Soviet Union – maybe even more than the Soviet Union wanted. To present such a model to somebody is a totally false idea.