South Korea’s Supreme Court on Thursday dismissed a complaint demanding the government disclose negotiations that led to a 2015 agreement between South Korea and Japan meant to settle the issue of Korean sex slaves, a contentious deal that fell short of putting on record whether Tokyo had directly forced the victims into sex slavery.

The pact, signed in December 2015 when the Korean and Japanese foreign ministers released statements vowing never to revisit the issue without mentioning coercion, prompted critics to study whether talks had discussed the use of force. Even after the deal, Japan publicly argued it never forced the victims into sexual slavery during its 1910-45 rule of the Korean Peninsula.

The Supreme Court said what had taken place during the 12 rounds of talks between chief negotiators of Seoul and Tokyo ahead of the pact signing was classified information by law.

Earlier, the trial court sided with a lawyer who asked for the full disclosure of negotiations that led to the deal, dismissing claims by the Korea’s Foreign Ministry that the revelation would break trust with Japan. The Korean people have the right to know, according to the ruling.

The appeals court, however, reversed the decision, saying disclosing negotiations could not only break trust, but also spark tension between the two neighbors.