SEOUL/TOKYO (Reuters) - Japan has decided not to take part in an international fleet review in South Korea next week after Seoul effectively asked Tokyo not to fly its “Rising Sun” flag on a warship, Japan’s defense minister said on Friday, the latest spat between the two sides.

Sailors fold the Japanese naval ensign after a flag lowering ceremony on the deck of Japanese helicopter carrier Kaga anchored near Jakarta Port ahead of its departure for naval drills in the Indian Ocean, Indonesia September 21, 2018. REUTERS/Kim Kyung-Hoon

Japan’s relations with both South and North Korea have long been strained by lingering resentment over its 1910-45 colonization of Korea, territorial rows and the issue of Korean girls and women forced to work in Japan’s wartime brothels.

Japan’s decision comes after South Korea this week asked participating countries not to fly flags at the bow or at the stern of their vessels, Defence Minister Takeshi Iwaya told reporters.

“When it comes to the Maritime Self-Defence Force ensign, domestic laws and regulations stipulate that it must be hoisted at the stern,” Iwaya said. “Regrettably, we have reached a decision that we cannot help forgoing the participation.”

Many people in both Koreas see the red-and-white flag as a symbol of Japan’s past military aggression and its colonization.

“The ‘Rising Sun’ flag is a war-crime flag that the 20th-century Japanese imperialists used when executing their barbaric invasions into our nation and other Asian nations,” North Korea’s state-controlled Uriminjokkiri website said.

“Planning to enter flying the ‘Rising Sun’ flag is an unbearable insult and ridicule to our people.”

In South Korea, articles about the controversy are among the most widely read on social media, with the president’s office receiving 250 petitions for the Japanese ship to be barred.

On Friday, the South Korean Navy said Japanese naval ships flew the ensign when they participated in fleet reviews in 1998 and 2008, but it had asked all ships at this year’s event to display national flags and the South Korean flag.

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The “Rising Sun” ensign, used by the Japanese Imperial Navy in campaigns around Asia and the Pacific before and during World War Two, was adopted by the Maritime Self-Defence Force in 1954.

Variations of the flag are used by the Ground Self-Defence Force and on the fatigues of some Japanese sailors, but some South Koreans liken it to Nazi symbols such as the swastika.

Prior to Iwaya’s comment, Japan’s top-ranking uniformed officer had signaled he was putting his foot down on the issue.

“Hoisting of the Maritime Self-Defence Force ensign is required by law,” Katsutoshi Kawano, the chief of staff of the Self Defence Forces, told reporters on Thursday.

“Members take pride in the ensign, and we will never go there with the flag unhoisted.”

South Korea’s foreign ministry had “conveyed our stance that the Japanese side should fully consider the Rising Sun flag’s emotional connotation to our people,” Foreign Minister Kang Kyung-wha said.

Japan was a key player in U.S.-led efforts to isolate and punish North Korea over its nuclear weapons and ballistic missiles.

Ties between the United States and North Korea have warmed since a summit in Singapore in June. U.S. Secretary of State Mike Pompeo said on Wednesday he was optimistic a visit to Pyongyang this weekend would bring progress toward North Korea’s denuclearization.

Japan and South Korea often trade barbs over disputed islands known as Takeshima in Japan and Dokdo in Korea.

Announcing Japan’s decision not to participate in the fleet review, Iwaya said that defense cooperation between Tokyo and Seoul remains extremely important.