Finland’s President Knows Putin Well. And He Fears for Ukraine.

HELSINKI — As the threat of a new Russian invasion of Ukraine grew, the European head of state with the longest and deepest experience dealing with Vladimir V. Putin fielded calls and doled out advice to President Emmanuel Macron of France and other world leaders desperate for insight into his difficult neighbor to the east.

“‘What do you think about this about this, what about this, or this?’ That’s where I try to be helpful,” said Sauli Niinisto, the president of Finland, as the harsh light gleaming off the snow and frozen bay poured into the presidential residence. “They know that I know Putin,” he added. “And because it goes the other way around Putin sometimes says, ‘Well, why don’t you tell your Western friends that and that and that?’”

Mr. Niinisto, 73, said his role was not merely that of a Nordic runner, shuttling messages between East and West, but of borderland interpreter, explaining to both sides the thinking of the other. The departure from politics of Angela Merkel, who for years as Germany’s chancellor led Europe’s negotiations with Mr. Putin, has made Mr. Niinisto’s role, while smaller, vital, especially as the drumbeat of war grows louder.

But Mr. Niinisto is not optimistic. Before and after his last long conversation with Mr. Putin last month, he said, he had noticed a change in the Russian. “His state of mind, the deciding, decisiveness — that is clearly different,” Mr. Niinisto said. He believed Mr. Putin felt he had to seize on “the momentum he has now.”

He said it was hard to imagine that things would return to the way they had been before. The opposing sides disputed the Minsk agreement that the Russians insisted be honored. The remaining options boiled down to Russia pressuring Europe and extracting demands from the United States for the foreseeable future, or, he said, “warfare.”

Such plain speaking has made Mr. Niinisto, in the fifth year of his second six-year term, wildly popular in Finland. He is compared by some to Urho Kekkonen, who took power in 1956 and ruled Finland for 25 years, during the so-called Finlandization period of the Cold War.

“We love him,” said Juha Eriksson, as he sold Reindeer pelts, canned bear meat and smoked salmon sandwiches in a market next to ice shards in the bay. “My generation had Kekkonen and he was the father of the country. And he is a little something like that. It’s a pity that he must leave office soon.”

Mr. Niinisto plays down his near 90 percent approval rating as consistent with his predecessors and dismisses the hyperbolic talk of his being some kind of Putin whisperer. “It’s an exaggeration that I somehow know more about Putin or his thinking,” he said. He is clearly cautious about upsetting a relationship he has nurtured over a decade, including many meetings, countless phone calls and a game of ice hockey. Asked who was better, he responded diplomatically, “I’ve been playing all my life.”

But he did point to some concrete benefits. After gaining support from Ms. Merkel, he said that he asked in 2020 if Mr. Putin would let Aleksei A. Navalny, the Russian opposition leader who accuses Russian operatives of poisoning him, to be flown to Germany for medical treatment. Mr. Navalny’s office later thanked Mr. Niinisto.

“He is a good person to call when you want to understand what is happening in the northeastern corner of Europe and especially if you want to understand the thinking of President Putin,” said Alexander Stubb, a former prime minister and foreign minister, who has accompanied Mr. Niinisto in meetings with Mr. Putin. “He’s a mastermind in power politics and in finding the right balance.”

That Mr. Stubb was so effusive about the president itself said something about Mr. Niinisto’s overwhelming popularity, and political dominance, in Finland, as political tensions between the two are widely talked about here.

Mr. Niinisto derives his power from a critical national security meeting that he runs and from the Constitution, which states that foreign policy is “led by the president of the republic in cooperation with the government,”

“It’s the president — pause — who is leading in cooperation,” Mr. Niinisto explained, making it clear who came first.

Finnish officials say that Mr. Niinisto sheds his diplomatic modesty in private, and is known for his long political memory, cutting style and mission creep. “I have been sometimes criticized for remembering too much my old history as minister of finance,” he said with a smile.

Domestic policy is the territory of the prime minister, currently Sanna Marin, a 36-year-old former cashier and climate change campaigner who raised Mr. Niinisto’s ire in January, according to Finnish political observers, when she told Reuters that it was “very unlikely” that Finland would apply for NATO membership while she was in office.

“I still say only that I see no major damages,” he said, with visible restraint. Asked if her statement was constructive, he said “I just repeat, no damages.”

The NATO option mattered in Finland as a strategic tool to manage Mr. Putin. In a country with an abundance of sayings about the incorrigible nature of Russians (“A Russian is a Russian even if you fry them in butter”) Mr. Niinisto recalled one about Russian soldiers, saying, “The Cossack takes everything, which is loose, which is not fixed.”

Despite recalling that Mr. Putin once said the friendly Finnish neighbor would become the “enemy soldier” if it joined NATO, Mr. Niinisto, who boasts about Finland’s impressive artillery, frequently asserts Finland’s right to become a member of the alliance. “I have said it to Putin too, very clearly,” he said.

Mr. Niinisto has also spoken directly to other leaders he suggested were threats to democracy. In a memorable joint news conference at the White House in 2019, he looked squarely at President Donald J. Trump and said, “You have a great democracy. Keep it going on.”

“He doesn’t respect institutions,” Mr. Niinisto said of Mr. Trump in the interview, whether it was the European Union or NATO. And the Finn considered the insurrection at the U.S. Capitol building a worrying sign for American democracy.

But in dealing with Mr. Putin, Mr. Niinisto tried to give Mr. Trump some pointers before a summit in 2018 in Helsinki, “actually behind that wall,” he said pointing across the room. Before a solicitous public performance that was widely considered a disaster for Mr. Trump, Mr. Niinisto told Mr. Trump that Mr. Putin “respects the one who is fighting back.”

Mr. Niinisto has said he told Mr. Biden something similar ahead of Mr. Biden’s call with Mr. Putin over Ukraine last month.

Besides the difficulty of dealing with Mr. Putin, Mr. Biden and Mr. Niinisto share another, and tragic, history. In 1995, Mr. Niinisto’s first wife died in a car accident, leaving him to raise his two young sons.

“I know his history,” Mr. Niinisto said quietly, adding that he might bring it up to the American president, who also lost his wife in a car crash as a young politician, “someday maybe if I had the possibility of having a longer sit with him.”

Mr. Niinisto also picked up the pieces. In 2009, then the speaker of Parliament, he married Jenni Haukio, then a 31-year-old director of communications for the National Coalition Party and now a poet. They have a 4-year-old son, and their dogs have become beloved national mascots.

Before the couple met, he was engaged to Tanja Karpela, a former Miss Finland who was a member of Parliament in an opposition party. They broke up in 2004, and Ms. Karpela now trains scent detection dogs that track Siberian flying squirrels.

The year of their breakup coincided with the devastating tsunami in Thailand, where he was vacationing with his sons and was nearly swept away. He survived by clinging high up on an electric pole for more than an hour. The traumatic event still seemed to shake the staid president, who lost a hundred countrymen that day. “People who were sitting beside you at breakfast,” he said.

That was a natural disaster. Now he hoped his relationship with Mr. Putin, and the “small moves” it might create, would help his partners avoid a man-made one in Ukraine.

“Dangerous times,” he said.