Is it sympathy for the devil to make a film about Japanese soldiers in World War II who are human beings, not fiends from a propaganda pamphlet? A film that shows American troops, like their adversaries, committing battlefield atrocities?

That’s what Clint Eastwood has done in “Letters From Iwo Jima,” the crowning achievement of his career, a work of great craftsmanship, conviction and dramatic power that portrays a crucial battle of the Pacific campaign from the vantage point of the enemy.

“Letters” makes a thought-provoking companion piece to Eastwood’s earlier Iwo Jima film, “Flags of our Fathers.” The American story was about lies we tell to make war appear heroic. Its Japanese counterpart concerns the grim business of fighting for survival.

At 76, Eastwood has the gifts of perspective and patience. Deliberately paced at 2 1/2 hours and pitilessly realistic, “Letters” holds shots long enough for us to think about them.

Well before the killing starts, Iwo Jima’s eerie black sand beaches and barren volcanic mountains are evocative of death. The Japanese troops’ sheltering caves have the feel of hillside tombs. The color is drained from the film palette until it is virtually black and white, making orange explosions and red jets of blood all the more garish. The war scenes are agonizing masterstrokes of timing and execution.

We meet the major characters in an unhurried way, delving deeper into their personalities in due time, often through the messages they mail home. Our first impression of the Japanese officers is how they treat their men (like vermin until the arrival of the humane and practical Gen. Kurabayashi, who doesn’t want good soldiers injured by flogging). In this late phase of the war, the Imperial Army has little hope of fending off the vastly superior U.S. force pushing toward the mainland. At best they can briefly delay the inevitable, yet fanatics in the upper ranks order them to hold their positions till the end and inflict the most casualties possible. No one is permitted to die until he has killed 10 Americans.

Although the battle is clearly unwinnable, the men are trapped in ancient Japanese codes of honorable self-destruction. “Suicide is the only option left,” one insists. Some, terrified of the Americans their rulers have demonized and running out of ammunition and food, swear death pacts with their comrades.

Others, like Saigo, a baker with a newborn daughter, have a stubborn will to live. After a futile day of shoveling out trenches, he writes to his wife, “Am I digging my own grave?” Never having met an American, he wonders why he should die trying to kill them.

He recognizes that commoners like him are farther removed from their aristocratic officers than from foot soldiers on the other side. One of their superiors, Baron Nishi (Tsuyoshi Ihara) is an Olympic equestrian who brings his favorite horse to the front, an ambassador from a mythical past when a noble hero – an Eastwood character, say – could gallop onto the scene and save the day. The urbane Kurabayashi and Nishi, who have spent time in the United States before the war, know that their government’s propaganda is false and count Americans as close friends. Yet as dutiful soldiers, they do what they must to annihilate them.

Ken Watanabe (“The Last Samurai”) brings a patrician bearing to Kurabayashi, a complex figure whose common sense pulls in one direction while his patriotic duty pushes in another. Seeing how poorly prepared his new command is for the coming assault, his expression is perfect: dismayed, embarrassed to be so shocked, and working hard not to reveal it.

Japanese pop star Kazunari Ninomiya makes Saigo an unforgettable nobody, good-hearted even when fear and exhaustion savage him like dogs tearing at a carcass. He’s the reverse image of his commander, doing nothing to advance the war effort and everything to survive for his family. Yet in the end Kurabayashi praises the lowly baker who has remained alive through the siege, saying “You are quite a soldier.”

Humanizing our old adversaries doesn’t erase their war crimes, and Eastwood doesn’t whitewash the brutality of Japanese militarism. His point is that the Emperor’s infantrymen were as much the victims of the Japanese war machine as the GIs they fought. Although the film’s dialogue is in Japanese, its message is clear. War, even when just, is catastrophic hell whatever uniform you’re wearing.