Actor Jeff Daniels is familiar with playing characters under pressure — “Gettysburg,” “Terms of Endearment,” “The Looming Tower” and “The Comey Rule.”

As Ronald Reagan to Jared Harris’ Mikhail Gorbachev in “The Brink of War,” the tension remains just as high. Out today, the drama focuses on the 1986 Reykjavik Summit, where the two leaders met to ease Cold War tensions.

“It’s an important film,” said the generational actor, who showed off his comedy chops in “Dumb and Dumber.”

“What happened that weekend in Reykjavik in 1986 — just as a story tells — is fascinating. The two leaders of two superpowers who hated each other, bitter rivals, decided it was best for the world if they got into a room together and tried to figure out how to do something about the 70,000 nuclear warheads that were pointed at each other with no missile shield to stop anything.”

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The summit ended without a final agreement; however, it built a foundation for the end of the Cold War.

“Somebody hits a button and you have 7 minutes to send one back their way,” Daniels said about nuclear warheads. “That was it. Mutually assured destruction and the impossibility of coming to any kind of agreement was probably what was going to happen.

“However, two years later, the Berlin Wall came down. This is a historical moment in world history — certainly U.S. and Russia history. It was important that we made a movie about just that weekend, what went on in that house in Reykjavik between those two leaders that weekend. It makes for great drama. It really does.”

Daniels admitted he knew little about the possibility of a nuclear catastrophe in 1986, as he was balancing his marriage, his 2-year-old son, acting and life in Michigan.

“I didn’t know the story,” said Daniels, who was raised in Chelsea, Michigan. “I was aware there was a meeting, OK, certainly not its focus.

“The danger of the world was kept away from people. Americans didn’t have access to information back then. After getting the role, I read about it and realized just how dangerous the world was on that weekend in October.”

That distance — the gap between what the public understood and what was actually unfolding — is part of what drew Daniels to “The Brink of War.”

“Two years later, the Berlin Wall came down,” he said. “But this was like the first step in that process.”

Daniels has played historical figures before — Washington crossing the Delaware, soldiers at Gettysburg — but this one felt different. This wasn’t mythologized Americana or battlefield reenactment. This was a transcript.

“What makes this different is that this actually happened,” he said. “In a lot of cases, in ‘The Brink of War,’ he actually said this in the room. We had transcripts.

“Michael Gunn, who wrote and directed it, was able to get to [then-Secretary of State] George Shultz before he passed away and asked a lot of questions about what went on in that house.”

The result is a film built on the exact words exchanged between two leaders who understood the stakes better than anyone else alive.

But authenticity comes with its own burden — especially when portraying Ronald Reagan, a figure so familiar that audiences arrive with their own version already in mind.

“You’ve got to pull audiences out of those preconceptions and into what he’s thinking and feeling,” Daniels said. “That was the trick.”

The emotional key that unlocked Reagan for him was “fear of failure.”

It wasn’t Reagan’s fear. It was his own.

“If you say ‘yes’ to doing Ronald Reagan without a clue as to how you’re going to pull it off, then you accept that challenge,” he said. “I had to figure it out. I surrounded myself with people like Jared Harris, J.K. Simmons, Hope Davis and others.

“They all bring their ‘A’ game. Now I had to work with great actors. They make you better. It became this job as an actor that I really looked forward to. When they say ‘action,’ what happens between ‘action’ and ‘cut’ is thrilling.”

Ironically, there was little rehearsal. The cast arrived ready, and the camera rolled. The tension of discovery — of not knowing what the other actor would give on take one — mirrored the tension of the summit.

“It makes for great drama,” he said. “It really does.”