The intrusion is still going on, a senior official told NBC News.
China's cyber spies have been reading the private emails of top U.S. officials since at least 2010, NBC News is reporting.
An unnamed senior U.S. intelligence official told NBC News spies targeted the personal emails of “all top national security and trade officials.”
Spies may also have collected officials' email address books -- "exploiting the(ir) social networks"-- and then sent malware to their personal contacts.
The intrusion was first detected in April 2010, according to a top secret National Security Agency briefing held in 2014, NBC News reported. U.S. officials called the intrusion “Dancing Panda” and later, “Legion Amethyst."
According to that senior official, government email accounts weren't accessed because they're more secure than the systems used for personal email.
In 2011, Google admitted that some U.S. officials' private emails had been compromised -- but the intrusion was not limited to Gmail, NBC News reported, citing the 2014 NSA briefing.
The intrusion was still active during the years Hillary Clinton used her own private email system between 2009 and 2013, while serving as secretary of state.
News of the intrusion follows NBC News' report last week that the Pentagon's Joint Staff emails were breached by Russian hackers.
At the time of writing, NSA had not responded to Nextgov's requests for comment.
(Image via Duc Dao/ Shutterstock.com)