South Korea ended months of speculation Wednesday by filing a complaint against Japan with the World Trade Organization (WTO).
Seoul has been threatening to take action since Tokyo began to restrict exports of three materials to South Korea in July.
Japan is the global leader in shipping fluorinated polyimide, photoresist and hydrogen fluoride which are needed for key South Korean tech products, including display panels and semiconductors.
Announcing the WTO complaint, the South's Trade Minister Yoo Myung-hee insisted Tokyo's decision to tighten controls on those particular export was a "discriminatory act directly targeting South Korea."
"It was politically motivated following our court rulings on the forced labor [of Korean workers during Japan's colonial rule]," Yoo added in comments carried by local news agency Yonhap.
Article 11 of the General Agreement on Tariffs and Trade prohibits regulations on export volumes except for items that seriously affect national security.
While Japan has claimed it cannot trust South Korea on security grounds, and last month removed its neighbor from a whitelist of preferential trade partners, Seoul claims there is no supporting evidence.
Onlookers are additionally concerned because the situation has been seen as urgent for South Korean tech firms and WTO arbitration is expected to take more than three years.
By Alex Jensen in Seoul