TOKYO (AP) — Japan says it has no plans to retract its tightened control on high-tech exports to South Korea, saying it involves Japanese internal policy review.

Chief Cabinet Secretary Yoshihide Suga said Tuesday the review was necessary to appropriately carry out export controls, and that Tokyo does not plan to negotiate its decision with Seoul.

Suga was responding to South Korean President Moon Jae-in’s request for a diplomatic solution, urging Tokyo to withdraw what he described as a politically motivated measure.

Japan tightened export approval for shipments of photoresists and other sensitive materials as relations between the two U.S. allies deteriorated over wartime forced labor and other issues.

Japanese Prime Minister Shinzo Abe and his ultra-conservative aides recently raised suspicion of South Korea’s alleged illegal transfer of sensitive materials to North Korea.