South Korean President Moon Jae-In on Thursday said his country’s 2015 agreement with Japan on its use of sex slaves during World War II was unworkable and “seriously flawed”, the Yonhap news agency reported.

“This runs afoul of the established universal principle of the international community for settling history issues, and above all, it was a political agreement that excludes the victims themselves and citizens,” Moon said about the deal.

The president’s statement comes a day after a task force – set up by the Foreign Ministry to review the deal – said the accord lacked a “victim-oriented approach”.

The dispute over the “comfort women”, a euphemism for tens of thousands of Korean women and girls who were coerced into working in Japanese military brothels from 1910 to 1945, has strained ties between the countries for decades.

Japan insists all compensation claims arising from the war were settled during a bilateral peace treaty signed in 1965. In 2015, it had apologised to the surviving victims and provided them 1 billion yen (Rs 54.5 crore) to help heal their “psychological wounds”. Surviving victims and activists, however, deemed the deal humiliating and said they were unhappy with Japan’s refusal to accept formal and legal responsibility for the wartime excesses.

“[The government] will prepare sincere and practical follow-up measures as soon as possible on the principle of a victims-centered resolution and people’s diplomacy to recover the honor and dignity of the victims and heal their wounded hearts,” Foreign Ministry Spokesperson Noh Kyu-duk said on Thursday.

Japan’s Foreign Minister Taro Kono had criticised the task force’s conclusions and also warned that the relations between the two countries would become unmanageable if Seoul backed out of the agreement, The Guardian reported.