South Korea and China look set for a renewed clash over what South Korean authorities believe are Chinese cyberattacks on multiple local academic organizations, potentially the latest flare-up in tensions recently heightened by a tit-for-tat visa spat over stronger COVID travel curbs.

Police opened a formal probe Wednesday to investigate hacking that had disrupted access to websites of at least 12 academic groups, a string of attacks that took place over the four-day Lunar New Year holiday ending Tuesday, a police official said.

The same day, a state-run cybersecurity think tank based in Seoul found Chinese hackers responsible for the latest breach. An official at the Korea Internet and Security Agency, the think tank, said it was working with police and on finding remaining “security holes” that require immediate attention.

Xiaoqiying, the Chinese group that claimed responsibility for the attacks, said on Telegram it had hacked into 79 websites and threatened to make public personal data stolen from there, a claim police have yet to verify. The group, openly anti-South Korea, had said it would target 2,000 websites run by the South Korean government. The hackers emphatically deny ties to the Chinese government.

A South Korean government official with knowledge of the matter said the websites hacked over the holiday were all run by organizations too small to arm themselves with security systems needed to fend off outside attacks.

“The hackers knew where they had to press and did not seem to be after some financial gains, though that’s more for police to look at,” the official said, noting the hackers appear to have meant to “show off” their cyber skills.

The cyberattacks come amid strained ties between Seoul and Beijing. Two weeks ago, China enforced tighter visa rules for South Koreans after Seoul imposed a short-term visa ban on Chinese travelers to prevent a spillover from a COVID crisis there. Beijing, which has recently eased some of the rules for South Koreans on official or urgent nonofficial business, describes its response as a “countermeasure,” downplaying concerns over “further retaliation.”

It is too premature to link the cyber breach to Chinese authorities given the lack of evidence. But animosity between the two countries now runs much deeper and that alone warrants a scrutiny of relations from the ground up, said Chung Jae-hung, director of the Center for Chinese Studies at the Sejong Institute.

The Indo-Pacific strategy South Korea revealed last year and is committed to expanding starting this year, Chung said, is what will lock the two Asian neighbors in a broader conflict as smaller clashes repeatedly test their ties.

“The policy embodies everything China finds uncomfortable, however we spin it,” Chung said of the initiative that South Korea aims to use for a bigger global imprint. Analysts see the plan as efforts to help reshape global order alongside the US, South Korea’s biggest ally and the rival China seeks to outpace.