There’s a scene in the new South Korean war movie “Operation Chromite” in which an American official challenges Gen. Douglas MacArthur’s decision to launch an amphibious invasion of Incheon during the Korean War.

“This is the riskiest military operation that I’ve ever encountered. Why the fixation on Incheon?” he asks.

Most South Koreans could have answered that question even before they flocked to the action flick starring Liam Neeson as MacArthur and a cast of Korean A-list actors. It opened in U.S. theaters Aug. 12.

The assault, which began Sept. 15, 1950, is celebrated as one of the most decisive battles in military history. It turned the tide of the war in favor of U.S.-led forces and paved the way for the recapture of Seoul from the North.

Imagine if MacArthur had listened to detractors arguing that the operation had only a 5,000-1 shot at success because of overwhelming challenges, including a narrow port, extreme tides and unfavorable terrain.

However, the 115-minute movie doesn’t dwell much on military calculations, and Neeson has only about 20 minutes of screen time, including just one brief scene with the South Korean lead Lee Jung-jae, who plays Navy Lt. Jang Hak-soo.

Instead, director John H. Lee opted for a classic good-versus-evil tale focusing on Jang and seven other South Korean spies who penetrate enemy lines to clear the way for the pivotal amphibious landing. Disguised as North Koreans, the team manages to steal key information needed for the invasion.

The action-packed sequences seem impossible, and much is exaggerated, but no spoiler alert is needed. The film is based on a real-life mission to land more than 70,000 troops at the western port city, then advance to reclaim Seoul, which had been captured by Soviet-backed North Korean forces at the start of the war.

Many American military leaders opposed MacArthur’s plan, but the legendary commander insisted that the seemingly insurmountable risks would give allied forces the element of surprise and allow them to attack the North from both directions.

“I am Douglas MacArthur. I win wars,” the general declares at one point in the film. Neeson mastered MacArthur’s mannerisms for the role, including wearing his hat at an angle and smoking a corncob pipe.

The success at Incheon reversed a series of North Korean victories and helped eventually push communist forces back toward the 38th parallel, although the war continued for three years before ending in an armistice instead of a peace treaty.

Many South Korean movie critics panned the film for ignoring the complexities of war and for its black-and-white portrayal of the communist North Koreans as stereotypical villains and the South Koreans as sentimental heroes.

They also complained about the small amount of screen time for Neeson and criticized his dialogue, which included iterations of famous quotes such as, “Old age may have wrinkled my skin, but when you lose your ideals, it wrinkles your soul.”

Neeson said he was drawn to the role by the simplicity of the script and a chance to play the legendary general.

“I thought it told a very complex story in a very palatable and easy way to follow for audiences. And it’s very emotional,” the Oscar-nominated actor told a July news conference in Seoul.

That it was. Backed by a heavy dose of suspenseful music, the main plot line is an increasingly bloody battle of wills between Jang and ruthless North Korean commander Lim Gye-jin, played by Lee Beom-soo.

There’s also an implausible love story involving Jang and nurse Han Chae-seon (Jin Se-yeon), who joins forces with the South Korean team after seeing her uncle executed for being a traitor.

Despite the criticism, the movie has packed theaters because it was released just in time for a heat wave in South Korea and tapped into patriotic feelings as tensions rise on the divided peninsula.

Park Soon Young, a 75-year-old veteran and military historian, said he enjoyed the movie even though it wasn’t entirely accurate.

“People need to see that a great deal of pain, effort and sacrifice go into defending the country,” he said. “Freedom is not free.”

The CJ Entertainment title, which was produced by South Korea’s Taewon Entertainment, beat out “Jason Bourne” to debut on top of the nation’s box office last month, and has earned more than $37 million. It opened in South Korea on July 27, the 63rd anniversary of the armistice signing.

That’s good news for investors. The film, which had a budget of about $12 million, was partially crowd-funded with a promise of returns once it hit the 5 million-viewer mark over the weekend.

The movie is mainly in Korean with English subtitles, except for the scenes involving Neeson.

gamel.kim@stripes.com Twitter: @kimgamel