What does the director imagine is the worst-case scenario? Nuclear war on the Korean Peninsula.

"We cannot escape from a nuclear war should a second war break out on the peninsula," he said. "When that happens, at least one of the two Koreas would disappear from Earth. So, that kind of war should not happen."

In the movie, the Korean Peninsula is on the brink of a nuclear war following a military coup in North Korea and a pre-emptive strike on the North by the United States. The country's "No. 1"

leader is found seriously wounded by an elite North Korean agent Um Cheol-woo (Jung Woo-sung). The agent then secretly takes the leader to South Korea with him seeking shelter and encounters Kwak Cheol-woo (Kwak Do-won),  the country's chief presidential secretary on diplomatic and security affairs. The two combine forces as they struggle to prevent nuclear war.

The movie is based on the popular 2011 webtoon of the same English name by the director, who is also a prominent webtoon author. The webtoon depicted a Korean Peninsula at crisis following the death of former North Korean leader Kim Jong-il.

Yang said he changed the political setting and characters in the original story to make a film adaptation years later because Kim actually died after the webtoon went into circulation.

"So, the film doesn't start with the death of Kim Jong-il but with the occurrence of a military coup."

After making the film, Yang also amended the original webtoon to reflect the current political situation on the peninsula. The comic series is currently available online both in Korean and English, according to him.

"Steel Rain" is the nickname of the existing multiple launch rocket system already operational in the US Army. The title is also what the given name of the two main characters -- one from North Korea and the other from the South -- means in English.

"Cheol-woo is a common name for men in their late 30s and early 40s in both countries," Yang said. The naming was intended to indirectly show that South and North Koreans are from the same tribe, he added.

It marks the director's second film after his successful debut in "The Attorney" (2013). Loosely based on the life of the late President Roh Moo-hyun's early years as a lawyer in Busan in the 1980s, the film starring Song Kang-ho sold about 11.4 million tickets across the country, a big success in the film market.

Jung complimented Yang as "a good filmmaker who has the courage to bring up issues that society must agonize over all together" each time he produces a film.

The actor said he watched multiple European documentary films on North Korea available on YouTube to learn the North Korean dialect for the role of Um Cheol-woo. "I had a North Korean language teacher who is female, but I was curious how men who live in Pyongyang speak."

Kwak, best known for his lead role in "The Wailing" (2016), said since his elite official character is fluent in speaking both English and Chinese, he had hard time memorizing dialog in the two foreign languages.

"I memorized English dialog all day long and fell asleep, exhausted," he recalled. "It was so difficult," he said with a deep sigh.

When questioned if he is concerned about the film's release on the same day with "Along With the Gods: The Two Worlds," one of the most anticipated films of the winter season, on Dec. 20, Jung said he doesn't think the two movies' target audiences will be overlapping.

"The two are of different genres and tell different stories," he said. "I hope this would help enlarge the market and have a positive influence on the industry." (Yonhap)