Samsung declined Friday to comment on Tokyo's latest move. Asked about Japanese trade restrictions during an earnings call Wednesday, Samsung's head of investor relations Robert Yi said the company was "facing difficulties" because of Tokyo's export controls "and the uncertainties that this new process would bring."
SK Hynix did not immediately respond to a request for comment. But the company warned last month of weaker sales for the second half of the year, and said it could not rule out production disruption if Japanese export curbs drag on. SK Hynix said it was trying to stockpile the affected materials as much as possible.
Tension between the two countries has been rising for months, stemming in part from Japan's colonial rule over the Korean peninsula in the early 20th century. South Korea's top court recently ruled that its citizens can sue Japanese companies for using forced Korean labor during the Second World War. Japan has denied that the two issues are linked.