Japan has tightened its control on exports to South Korea of several chemicals crucial to the production of chips and displays used in smartphones and televisions. It is also preparing to remove South Korea from "white-listed" countries that face minimum restrictions on high-tech exports with national security implications — just as bilateral relations turn frigid amid the row over wartime labor. The latest development in the troubled Japan-South Korea relationship makes it all the more urgent that steps are taken to get diplomatic relations back on track.

Effective Thursday, South Korea-bound exports of fluorinated polymide, hydrogen fluoride and resist were removed from a list that allows expedited exports. Exporters are now required to file individual applications to sell the chemicals to South Korea and go through a screening process that takes about 90 days. Japanese manufacturers have a large share of each of the three chemicals — accounting for about 90 percent of the global supply of resist, for example — and major South Korean high-tech manufacturers such as semiconductors rely heavily on Japanese imports. The decision has raised concern in South Korea that its industries will face serious damage if the supply of chemicals from Japan gets clogged due to the screening of export applications.

Tokyo explains it is tightening the regulations "for the purpose of implementing proper export controls for security purposes" and rebuffs the charges from South Korea — which has threatened to take the case to the World Trade Organization — that the measure runs counter to free trade principles. At the same time, Chief Cabinet Secretary Yoshihide Suga has acknowledged that the reasons behind the decision include the failure of South Korea to come up with a "satisfactory solution" to the row over Koreans mobilized to work for Japanese companies during World War II.