The South Korean National Security Council says relations with Japan have been "seriously hurt" by a Japanese claim this week to several disputed islands.
South Korean National Security Council Chairman Chung Dong-young says Seoul will not tolerate Japanese challenges to its sovereignty over islands in the Sea of Japan. He presided over a council meeting Thursday to respond to Japan's Shimane Prefecture decision Wednesday to designate February 22 as "Takeshima Day."
Takeshima is the Japanese name for a handfu l of tiny, rocky islands, which lie between the Korean Peninsula and Japan. Koreans call the islands "Dokdo," and have been the de facto administrators since the end of World War II.
Japan's national government has distanced itself from the move by Shimane Prefecture but it has not been enough to quell widespread anger in South Korea.
Mr. Chung says the Japanese move is similar to a "second invasion" of the Korean Peninsula - a reference to Japan's occupation of Korea from 1910 to 1945.
Mr. Chung, who is also Unification Minister, says the Japanese law weakens attempts to strengthen regional partnership between the two countries.
South Korea now will boost its presence on the islands, which may include increasing Coast Guard presence and perhaps installing phone facilities.
South Korean lawmakers unveiled a proposal Thursday to erect a giant statue on the islands of Admiral Yi Sun-shin, a 16th century admiral beloved here for repelling Japanese naval invaders.
On Wednesday, South Korean officials said they would ease environmental restrictions on tourism to the islands, allowing more Korean citizens to visit.
Separately, South Korean authorities say Japanese reconnaissance planes flew within 60 kilometers of the islands Wednesday, and then turned around after several warnings from the South Korean military.
South Korean media have been saturated with reporting and commentary on the dispute, which stirs bitter memories of Japan's harsh colonial rule.
Despite the controversy, South Korean and Japanese authorities have vowed to keep the island dispute separate from other diplomatic efforts, such as talks to end North Korea's nuclear weapons programs.