Samsung Electronics and other chipmakers are experiencing trouble finding alternative suppliers for these materials, and industry sources said Sunday there are only a few days' worth of supply remaining in stock. Japan accounts for 70 to 90 percent of the production of the materials being targeted.

Lee flew to Japan against this backdrop, with multiple sources saying he was scheduled to sit down with business figures during his stay.

Samsung Electronics declined to provide Lee's specific schedule or itinerary. 

Earlier Sunday, Economy and Finance Minister Hong Nam-ki and Kim Sang-jo, chief of staff to President Moon Jae-in for policy, met with representatives from "major companies on the uncertainty over external economic conditions," according to Cheong Wa Dae.

The presidential office didn't disclose the names of the companies or their representatives. But a government source said Hong and Kim had pushed for a meeting with heads of the country's five biggest conglomerates: Samsung, Hyundai, LG, SK and Lotte.

Lee departed for Japan a little later than originally scheduled, fueling speculation that he attended the meeting with Hong and Kim before leaving the country.

Lee arrived at Haneda Airport in Tokyo around 9 p.m., but refused to answer questions from South Korean reporters about whom he'll meet in Japan and how long he'll stay there. (Yonhap)