TOKYO (AP) — Japan has defended its decision to impose export restrictions on South Korea, citing national security concerns and its obligation as part of the international community to keep tabs on sensitive technology transferrable for military uses.

Chief Cabinet Secretary Yoshihide Suga said Tuesday the step does not violate free trade principles.

Japan said Monday it will impose restrictions on exports of semiconductor-related materials to South Korea. Officials cited a lack of trust between the Asian neighbors, stemming from disputes over the issue of Koreans forced to work as laborers during World War II.

Suga said Japan will closely watch the possible impact on Japanese companies.

The trade ministry said exports related to manufacturing computer chips, such as fluorinated polyimides used for displays, must apply for approval for each contract beginning Thursday.