South Korea’s Minister of Foreign Affairs Kang Kyung-wha on Wednesday urged Japan to make a “prudent” response to rulings on Japan’s wartime use of South Korean forced labor, in a phone conversation with her Japanese counterpart amid an intensifying diplomatic row.

According to Seoul’s Foreign Ministry, Kang Kyung-wha and her Japanese counterpart Taro Kono exchanged views on the South Korean top court’s recent rulings that ordered Japanese firms to compensate South Korean victims forced into labor during Japan’s occupation of the Korean Peninsula.

“Minister Kang explained our government’s position on the rulings and urged a prudent response from Japan. The two ministers will continue to closely communicate with each other from now on,” the ministry said in a press release.

Relations between South Korea and Japan have soured since the Supreme Court ruled that Japan’s Nippon Steel & Sumitomo Metal must compensate four South Koreans forced to work at its steel mills during Japan’s colonial occupation.

A separate ruling last month in favor of 10 South Koreans forced into labor and Seoul’s announcement to disband a Japanese-funded foundation aimed at supporting South Korean victims of Japan’s wartime sexual enslavement further worsened their relations.

Japan has fiercely hit back, with high-ranking officials and lawmakers denouncing the rulings as unacceptable and signaling tough countermeasures.

Tokyo has said the ruling on forced labor is in violation of a 1965 treaty and overturns the legal basis of South Korea-Japan relations, calling on Seoul to take “appropriate action.”