Sources: in late 2020, the NSA discovered that Chinese hackers had access to Japanese defense networks, with the problem persisting until at least early 2021 (Ellen Nakashima/Washington Post)

Ellen Nakashima / Washington Post:
Sources: in late 2020, the NSA discovered that Chinese hackers had access to Japanese defense networks, with the problem persisting until at least early 2021  —  Tokyo has strengthened its defenses after a major cybersecurity breach, but gaps remain that could slow information-sharing with the Pentagon