Japan has said that South Korea shunned its requests for talks over its concerns about the smuggling of raw material with military warfare potential for "a couple of years", thus significantly undermining trust and forcing it to impose tighter export control measures.
A senior Foreign Ministry official told reporters yesterday on condition of anonymity that Seoul has not done its part to warrant a place on Tokyo's white list of "trusted" countries that it sees as presenting no risk of weapons proliferation.
South Korea has, since 2004, enjoyed preferential trade treatment as the only Asian country on the 27-nation list. But its place could be struck off as soon as this month following a Cabinet order.
The stricter controls imposed since Thursday last week do not constitute a ban, but Japanese companies wanting to sell the three materials - fluorinated polyimide, photoresists and hydrogen fluoride - to the South Koreans will need to apply for approval for each contract, just as they had to before 2004.
"To keep an effective control over sensitive substances and technologies from a security perspective is Japan's responsibility as a member of the international community," the official said.
He added that "logically speaking", the restrictions could be removed so long as Japan's concerns are properly addressed, as he stressed Tokyo's commitment to the global rules-based order.
In this vein, he disputed assertions - even if it may seem coincidental - that the move was in retaliation over a deepening feud on wartime labour, after the South Korean Supreme Court ordered Japanese companies to compensate the workers.
Japan insists the issue was fully settled in a 1965 treaty to normalise bilateral ties. The official said yesterday that, on that basis, "legal issues and emotional issues should not be mixed up" as it undermines an international contract.
These comments came as Japanese and South Korean trade officials met in Tokyo yesterday for their first working-level talks since the curbs took effect.
But they did not go far in reconciling their differences during the 5½-hour meeting, even though both sides explained their case.
Separately, the United States' top diplomat for East Asia, Mr David Stilwell, who is in Tokyo for an introductory visit, told public broadcaster NHK that the US has no plans to intervene or mediate in the trade feud between its two security allies.
Seoul has gone on a diplomatic offensive to fight Tokyo's measures, and has sent government officials to Washington to plead its case.
South Korean Foreign Minister Kang Kyung-wha also spoke by phone to US Secretary of State Mike Pompeo on Wednesday, expressing concerns that the curbs will hurt the global world order.
The outrage stems from the fact that the three affected materials, of which Japan controls up to 90 per cent of the world's supply, form the lifeblood of South Korea's vital semiconductor industry.
Any disruption of chips and displays made by companies such as Samsung Electronics and SK Hynix could, in turn, affect the production line of Apple and other smartphone makers. Fluorinated polyimides are used in smartphone displays, photoresists are used to form circuit patterns on semiconductor wafers, while hydrogen fluoride is used as an etching gas in the chip-making process.
But Japan says the materials can, respectively, be used to make combat plates, radars and chemical weapons such as sarin gas.
Japan's Chief Cabinet Secretary Yoshihide Suga, commenting on the call between Dr Kang and Mr Pompeo at a regular news conference yesterday, said any criticism is "improper" as the curbs are clearly based on security.