South Korean lawmakers from both the ruling and opposition parties visited South Korean-controlled, Japanese-claimed islets in the Sea of Japan on Monday, possibly rekindling bilateral friction over a territorial dispute of long-standing.
The office of Lee Chan Yeol, chairman of the Education Committee in the National Assembly, confirmed the group visited the pair of rocky islets known as Dokdo in South Korea and Takeshima in Japan.
The Japanese government had called through diplomatic channels for the group not to travel to the disputed islets. A group of South Korean parliamentarians also visited the islets last May.
In Tokyo, Chief Cabinet Secretary Yoshihide Suga said in a press conference the Japanese government lodged a protest with the South Korean government through diplomatic channels.
"This Takeshima visit by the lawmakers was utterly unacceptable in light of our country's position on the sovereignty of Takeshima," the top government spokesman said.
The visits always strain relations between the East Asian neighbors with a difficult relationship at the best of times because of historical issues. Yet both Seoul and Tokyo are now also focused on working closely together to compel North Korea to abandon its nuclear weapons.
Thirteen lawmakers, from both the ruling Democratic Party and the main opposition Liberty Korea Party, made the trip to the islets, which are located roughly an equal distance from the Korean Peninsula and Japan's main island Honshu.
Lee said in a Facebook post on Monday morning that the purpose of the visit was to repudiate Japanese claims in school textbooks that the islets are part of Japan, and to propagate a "correct understanding of history."
South Korea has stationed security personnel on the islets since 1954 and constructed lodgings, a monitoring facility, a lighthouse, and port and docking facilities.