In early 2014, after Russia annexed Crimea, pro-Russia separatists in the north of Ukraine, with Russian President Vladimir Putin’s backing, seized parts of the border area near Donetsk. After those rebels were blamed for shooting down a Malaysian passenger jet flying over eastern Ukraine that summer, President Obama convinced Europe to impose economic sanctions, which have devastated the Russian economy. Putin also withdrew many of the Russian military advisers, allowing local fighters to assume high-ranking positions in the leadership.

One of those local fighters, Fyodor Berezin, became the deputy defense minister of what the rebels call the Donetsk People’s Republic, and now trains new recruits in tank artillery. Berezin is an unlikely leader in any war: before all this took place, he was known as a sci-fi novelist in the genre of “historical fantasy.” Readers may be familiar with the American version of this style of writing, which includes books about, for instance, how the outcome of the Civil War might have changed if Robert E. Lee had machine guns. Berezin’s novels typically involve heroic struggles between an imaginary U.S.S.R. spreading triumphant Communism all over the world while kicking around a weakened and marginalized U.S.A.

The fantasist of war is now waging one. I got word to Berezin on the front lines and he agreed to journey to a Donetsk pub known as Three Fat Men. We both fired up our Skype software and had the following conversation, which has been edited and condensed.

How did you transition from being a writer in the field of historical fantasy to a soldier in the field of Ukraine?

That was easy. In 2009, I had already written a novel about war in the Ukraine: “War 2010: The Ukrainian Front.”

In some of your novels, local conflicts escalate to world wars. Do you think that will happen in the real world in Ukraine?

Thank God, tension has dissipated now. When I wrote the novel, I thought we were going to celebrate the hundredth anniversary of World War I with World War III.

Do you think the current tensions between the U.S. and Russia will lead to a third world war?

There is no direct conflict between the U.S. and Russia. There is not even direct conflict between Ukraine and Russia. I am a representative of military forces of the Donetsk People’s Republic. We might have weapons and ammunition supplied by Russia, but we fight against Ukraine. By ourselves. As rebels.

Has becoming a soldier changed your life as a writer?

Last month, I was accepted for publication in an American anthology that was to be published by M.I.T., in Boston. At the last minute, when they found out who I was, they removed my short story. They didn’t publish it, even though a half-year before we had an agreement.

In Moscow, Dmitry Lvovich Bykov, the author of biographies of Pasternak and Gorky, called the conflict in Ukraine a “writer’s war.” Do you agree, and what does he mean?

Bykov is an odious personality. He is just trying to draw all the attention to himself. That is his personal position. He is very surprised that there is a part of the intelligentsia that participates in the war. He supports the Ukrainian government.

You don’t read him?

Recently I have been reading a lot of Neal Stephenson.

The author of “Cryptonomicon.”

I used to read a lot of Tom Clancy. Some publishers here call me the Russian Tom Clancy. Like me, he has predicted a lot of things that have come true. In one of his books published a long time ago (“Debt of Honor,” 1994), he described a plane crashing, not into a skyscraper, but a joint session of the U.S. Congress. The difference is not that big. And in another book (“Executive Orders,” 1996), he also predicted the war in Iraq.

Your latest novel is “Ukrainian Hell.” Can you tell me more?

This is a reprint of a novel, which came out in 2011, under a new title, and was written before the war.

Are your fellow-soldiers reading your book?

I have met several dozen people who have read them and who were very surprised that I had made several predictions and gotten them right.

Such as?

In my novel “Big Black Ship,” I write about a non-human civilization that is not on planet Earth, and this civilization is developing according to its own history. I invented this big black submarine in it, armed with a huge torpedo thirty-three metres long and two-and-a-half metres wide. It blows up only when it approaches the enemy harbor, and then it destroys the entire city. About ten years after it was published, I was talking to some Soviet engineers, and I found out that these things I invented secretly existed.

In Clancy’s books, the U.S. always beats the Soviet Union, so who got that prediction right? Clancy or Berezin?

In my novels, it’s Russians beating Americans, so it’s obvious which side I’m on! There is also alternative history in my novels. It says that a weak United States fights with the mighty and powerful Soviet Union that controls nearly all the world on the globe.

How has being a soldier changed the way you might write your next novel?

Let me say that the main canvas of my novels won’t change. As a writer I am enriched by seeing lots of events which define an external, outer character. But there is the internal soul, the imagination, and other impressions that will help me write my next books. Also, I would like to write some books that would be non-fictions—not documentary, not fiction, but autobiography, just about this war.

Have you encountered anything on the battlefield stranger than the things you have made up in your books?

I have seen a lot of things that are more horrifying than anything I have written in a novel. For example, barbarian shootouts in inhabited urban cities that are nowhere near those in my books.

Horrifying, yes. But stranger than fiction?

If I were describing losses in a particular battle, and I said that our losses were one to one thousand for the enemy, I would be mocked as a fiction writer. But things like this have happened to us. When we engaged in an operation in Slavyansk we had a similar ratio with losses. Another time, a young fifteen-year-old militia man on our side, with just one flare gun—the kind you use in sports—dropped a helicopter in the Ukrainian army by firing into a half-open window.

Your novels include mystical forces and miracles. Do such things ever happen to you on the battlefield?

Because I am atheist, I look at these things with sarcasm. Nevertheless, a lot of events that you could ascribe to mystical coincidences have happened in my life, and at war especially.

For example?

There was a conflict with some neighboring troops, a territorial quarrel, and they showered me with a box of bullets from a machine gun. I was covered in dirt from the dust kicked up by the shells, but not one bullet touched me. And then, one week later, the general in charge of this unit and I were drinking cognac.