Wenbin warned Japan not to “throw mud,” and said that cyberattacks are a common issue faced by all countries to refute the Japanese government’s belief about China’s responsibility as Tokyo police investigate.

“Groundless speculation should not be allowed. China is firmly opposed to any country or institution using cyberattacks to throw mud at China or to serve the despicable political purposes with cybersecurity issues,” Wenbin said, according to AP. “China is willing to strengthen dialogue and cooperation with all parties to jointly address cybersecurity threats.”

On Friday, the White House issued a joint leaders’ statement with Japan that emphasized the need to strengthen cybersecurity and information security.

For more reporting from the Associated Press, see below.

The cyberattacks on Japanese companies and research organizations includes an attack made on the country’s space agency, the Japanese government said.

Police have forwarded the case involving attacks on the Japan Aerospace Exploration Agency to prosecutors for further investigation, Chief Cabinet Secretary Katsunobu Kato told reporters.

Police believe a series of hacks of JAXA were conducted in 2016-2017 by “Tick,” a Chinese cyberattack group under the direction of a unit of the People’s Liberation Army, Kato said.

A suspect in the JAXA case, a Chinese systems engineer based in Japan, allegedly gained access to a rental server by registering himself under a false identity to launch the cyberattacks, Kato said, citing the police investigation.

NHK public television said another Chinese national with suspected links to the PLA unit who was in Japan as an exchange student was also investigated in the case. Both men have since left the country, it said.

Police are investigating the attackers’ intent and methods while also pursuing scores of other cyberattacks that they suspect are linked to China’s military, Kato said.

“The involvement of China’s People’s Liberation Army is highly likely,” said Kato, who added that no actual data leak or damage has been found so far, but police are urging the companies to strengthen their protection.

Japan’s Defense Ministry said cyberattacks are part of rising security threats from China as it becomes more assertive in the region—a shared concern discussed in April 16 talks at the White House between U.S. President Joe Biden and Japanese Prime Minister Yoshihide Suga.