In a potentially far-reaching decision, South Korea's Supreme Court ruled that a major Japanese steelmaker should compensate four South Koreans for forced labor during Japan's colonial rule of the Korean Peninsula before the end of World War II.

The long-awaited ruling, delivered Tuesday after more than five years of deliberation at Seoul's top court, could have larger implications for similar lawsuits that are pending in South Korea and will likely trigger a diplomatic row between the Asian U.S. allies.

Japanese Prime Minister Shinzo Abe said Tokyo will respond "resolutely" to the ruling, which he described as "impossible in light of international law." He said the ruling violated a 1965 treaty between Seoul and Tokyo that was accompanied by Japanese payments to restore diplomatic ties. Japanese Foreign Minister Taro Kono said Japan could potentially take the case to the International Court of Justice.

"Today's ruling by the South Korean Supreme Court has one-sidedly and fundamentally damaged the legal foundation of Japan-South Korea relations," Kono said.

South Korean President Moon Jae-in had no immediate reaction to the ruling. South Korean Foreign Ministry spokesman Noh Kyu-duk said Tokyo and Seoul "should gather wisdom" to prevent the ruling from negatively affecting their relations.

The court said Japan's Nippon Steel & Sumitomo Metal Corp. should provide compensation of 100 million won ($87,680) to each of the four plaintiffs, who were forced to work at Japanese steel mills from 1941 to 1943. Among them, only 94-year-old Lee Chun-sik has survived the legal battle, which extended nearly 14 years.