Cyber spies linked to China have accessed the private emails and email address books of "many" top Obama administration officials, according to a senior U.S. intelligence official and a top secret document obtained by NBC News.
The intrusion, first codenamed "Dancing Panda" then "Legion Amethyst," was detected in April 2010, according to a top secret NSA briefing from 2014.
Government email accounts assigned to the officials, which are more secure, were not hacked.
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The names of the government officials whose emails were accessed were not disclosed.
The time period overlaps with Hillary Clinton's use of a private email account while secretary of state.
A senior official told NBC News the intrusion into personal emails in ongoing.