SEOUL - In an escalation of its bitter dispute with Japan, South Korea decided Thursday to scrap a military intelligence sharing agreement with Tokyo, opening a new divide in trilateral security cooperation between the U.S., Japan, and South Korea.

South Korea's presidential Blue House said Thursday it is not in its national interest to continue a deal signed for the purpose of exchanging sensitive military information with Japan. Seoul will inform Tokyo of its decision before the Saturday deadline to renew the General Security of Military Information Agreement, or GISOMIA, the South Korean statement said.

The decision will worsen tensions between South Korea and Japan, who are involved in a dispute rooted in Japan's use of forced labor during its colonial occupation of Korea. The move also threatens to further upend security cooperation on U.S. priorities such as North Korea and China.

In South Korea, Anti-Japan Emotions Run High on 'Liberation Day'

In announcing its decision, South Korea cited Japan's recent decision to remove Seoul from its list of trusted trade partners.

"The rationale was that a national security problem had arisen due to a breach of trust, yet no concrete evidence to support those allegations was presented," the Blue House statement said.

"Under these circumstances, the Government of the Republic of Korea decided that maintaining this Agreement, which was signed to facilitate the exchange of sensitive military information, does not serve our national interest," it added.

The General Security of Military Information Agreement, or GSOMIA, was signed in November 2016. It's not clear what the immediate impact of its termination will be.

"I hope there is no impact on policies but there will be an impact on military and intelligence operations," says David Maxwell, a former U.S. special forces colonel in the U.S. Army, who served in South Korea. "Information will be shared through the US middle man unless South Korea or Japan makes the situation worse by adding caveats such as the information they provide cannot be shared with a third party."

South Korea's Foreign Minister Kang Kyung-wha said the decision to withdraw from GSOMIA is a "separate issue from the South Korea-U.S. alliance," according to South Korea's Yonhap news agency. The decision, she says, was made due to a "trust issue" between Seoul and Tokyo, Yonhap reported.

But the move cannot be separated from Seoul's alliance with Washington, insists Maxwell, now with the Washington-based Foundation for Defense of Democracies. "It damages the national security of all three countries though South Korea suffers the worst," he said.

The U.S. military did not immediately respond to VOA requests for comment.

Japan Says S. Korea Failed to Explain Reason for New Trade Restrictions The two countries are removing each other from lists of preferred trading partners

Trade moves

Japan last month removed South Korea from its "white list" of trusted trade partners and restricted exports of high-tech materials to South Korea. The materials are used to produce semiconductors and displays in smartphones and other electronics that serve as the backbone of South Korea's export-driven economy.

Japan's moves are widely seen as retaliation for recent South Korean court rulings ordering Japanese companies to compensate Koreans who were forced to work during Japan's colonial occupation of Korea.

Seoul retaliated earlier this month by removing Japan from its own "white list" of countries that enjoyed minimal trade restrictions.

South Korean President Moon Jae-in last week signaled a deescalation in its trade dispute with Japan, saying he would "gladly join hands" with Tokyo if it chooses dialogue.

But Leif-Eric Easley, a professor at Ewha Womans University in Seoul, says the Moon government may see the GISOMIA decision as a "symbolic, low-cost way of signaling resolve" to Tokyo. He warned, however, the move could backfire.

"Tokyo may become more likely to escalate economic pressure. South Korea may be seen by Pyongyang, Beijing and Moscow to be weakening its alliance cooperation with the United States, leaving Seoul more exposed to regional geopolitics," said Easley.

Historical dispute

The trade dispute is the latest flare-up in tensions rooted in Japan's brutal 1910-1945 occupation of the Korean peninsula. A major source of friction is how to compensate those forced into labor and sexual slavery in the colonial era.

US Marines Chief Acknowledges Worries on Japan-Korean Ties Gen. David Berger says he is concerned about deteriorating relations between Japan and South Korea, both key regional allies, but expresses hopes politicians will work out a resolution

Japan says the reparations issue was resolved with a 1965 treaty that normalized Japan-South Korea relations. Japan has complained that subsequent South Korean governments have not accepted further Japanese apologies and attempts to make amends.

The issue re-emerged last year after South Korea's Supreme Court ordered Japanese companies, including Mitsubishi Heavy, to compensate Korean forced labor victims. The companies have not complied with the rulings, leading some victims to begin the legal process to seize or liquidate the companies' assets in Korea.

Japan says the rulings are unacceptable. But South Korea says it cannot overturn them, saying that doing so would amount to interference in South Korea's independent court system.