The Japanese space agency JAXA has been hit by a series of cyberattacks since it reported a cyber incident last year.

During a press conference on Friday, Japan’s Chief Cabinet Secretary Yoshimasa Hayashi acknowledged that hackers “from outside of Japan” have attacked JAXA several times since last year. He claimed that sensitive information related to rockets and satellites was not affected by the hacks.

The country’s security officials are conducting an “in-depth” investigation of the attacks and will take preventive measures to protect the agency’s networks from future intrusions, according to Hayashi. Part of the affected JAXA network was shut down during the investigation.

Hayashi added that securing cyberspace is becoming more complicated and the government will work to bolster protections in that field.

JAXA is responsible for developing and launching satellites into orbit and is also involved in advanced missions such as asteroid exploration and potential human exploration of the moon.

The agency has suffered multiple cyber incidents since 2016 when it was among 200 Japanese companies and research institutes allegedly targeted by Chinese military hackers.

Last year, unknown hackers reportedly targeted the agency’s network server but failed to gain access to information “that is particularly important for the operation of rockets and satellites,” the agency told Recorded Future News at the time.

Sources at the science ministry and JAXA told the outlet Nippon that during the latest attacks the hackers targeted a JAXA server in order to get access to the agency's general business operations. That may have led to breaches of communications between the agency and external organizations with which it has confidentiality agreements, such as Toyota.

Citing anonymous sources, the outlet NHK reported that the personal information of JAXA staff may have been leaked from its servers during the attacks. The agency told NHK that an investigation is still underway regarding data that may have been compromised but declined to provide details due to security concerns.

JAXA did not respond to a request for comment.

In February, Japan’s cyber official, Kazutaka Nakamizo, said the country faces increased cyber threats to its critical infrastructure, particularly from China. Speaking to Recorded Future News, Nakamizo did not specify which attacks they believe were linked to Beijing. 

Last August, suspected Chinese hackers breached Japan’s cybersecurity agency and potentially accessed sensitive data. According to media reports, China was also behind another incident that affected Japan’s port of Nagoya last year.