WASHINGTON -- Bilateral relations between South Korea and Japan have dipped to their lowest ebb, also affecting the countries' three-way cooperation with the United States, a congressional report said.

The Congressional Research Service (CRS) report noted the new Biden administration may be mulling ways to rebuild trust between the two US allies.

"Japan's relations with South Korea are perennially fraught due to sensitive historical issues from Japan's colonization of the Korean Peninsula from 1910 to 1945," said the report, updated last Tuesday.

"Since 2018, these relations marked their lowest levels in decades," it added.

Seoul-Tokyo relations quickly began to deteriorate in mid-2019 when Japan placed restrictions on South Korea-bound exports of three key materials used to produce semiconductors and display panels.

Japan also removed South Korea from its list of trusted trade partners.

Many in Seoul believe the measures were aimed at retaliating against a Seoul court decision that ordered Japanese firms to pay compensation to Koreans forced into free labor during Japan's colonial rule of Korea.

Tokyo denies any link between its trade actions and the Seoul court decision, but continues to demand South Korea nullify the court decision.

The report said the deterioration in the bilateral relations may undermine the United States' three-way cooperation with the two Asian allies.

"A series of actions and retaliatory countermeasures by both governments involving trade, security, and history-related controversies in 2018 and 2019 caused bilateral relations to plummet, eroding US-South Korea-Japan policy coordination," the report said.

US President Joe Biden has repeatedly highlighted the importance of US allies, especially those in Asia, to deal with China, as well as North Korea.

The report suggested the new US administration may work to help mend ties between the two US allies.

"The Biden Administration has pledged to rejuvenate US alliances and may be considering how to facilitate trust between the two US allies to foster more effective trilateral cooperation," it said. (Yonhap)