WASHINGTON — U.S. authorities have disrupted a cyber operation that officials say was linked to China and involved attempts to penetrate some of America's most sensitive government networks.

The Justice Department said it seized domains associated with two hacking platforms, QScan and QTRouter, which investigators say were used during the campaign. Court documents identified the Department of Energy, Department of Health and Human Services and National Institutes of Health among organizations affected, alongside several private companies in the United States and South Korea.

Officials said the campaign involved both successful intrusions and unsuccessful attempts. Cyber authorities also identified efforts involving the U.S. Senate and a U.S. hospital in 2026.

The operation reportedly dates back several years, highlighting the continuing security challenge facing U.S. government agencies, financial institutions, research organizations and critical infrastructure.

The latest disruption underscores the growing national-security stakes surrounding state-linked cyberattacks as Washington increases pressure on foreign hacking networks.

China's embassy in Washington rejected the accusations, saying Beijing opposes cyberattacks and objected to what it described as U.S. efforts to use cybersecurity allegations against Chinese companies.

The Justice Department's action does not necessarily mean all activity connected to the campaign has ended, but the seizure of the domains is intended to disrupt the infrastructure used by the alleged attackers.