TOKYO (AP) — The head of Japanese whiskey maker Suntory said Friday that merging work cultures remains a major challenge, more than 20 months after his company acquired the U.S. maker of Jim Beam bourbon.

Takeshi Niinami, the president and CEO of Suntory Holdings Ltd., said integration is difficult because Japanese and American employees have differing career aspirations and compensation systems.

He recalled the fictional but all-to-real confusion in the movie "Lost in Translation" when actor Bill Murray is depicted filming a whiskey commercial, for Suntory's Hibiki brand.

"I understand this type of situation can and will happen," Niinami said at a Tokyo news conference. "Beam and Suntory definitely have differences. ... This is not an easy task. But I'm ready for it."

Suntory, in a bid to go global, bought the former Beam Inc. for $16 billion in April 2014, and hired Niinami as the first outsider to lead the company in October of that year.

The combined Beam Suntory will have to concentrate on integration for at least three to four years, Niinami said, so it has no interest in Dutch beer Grolsch, Italy's Peroni or any other acquisitions for now. The two European brands are on the market as part of the merger of AB InBev and SABMiller.

Niinami said that while Japanese employees generally don't leave a company, Americans have a three-to-five-year horizon, and will leave if they can't find a better job within the company after that.

"I don't have solution yet in my hand, but at first definitely we have to recognize differences like that," he said.

He likened Suntory's approach to globalization to the process of making the best whiskey on Earth. "That takes a lot of time," he said. "We have to be patient."