The breach compromised the data of more than 800,000 employees, according to the Postal Service.
US Postal Service hacked; Chinese hackers suspected; the compromised data includes names, dates of birth, Social Security numbers, addresses, dates of employment, emergency-contact and other personal-information. The data of every employee, including the postmaster general; is exposed (around 800,000 people).
No customer credit-card information from post offices or online purchases at usps.com is breached.
The intrusion into the U.S.P.S. appears to be carried out by a sophisticated-actor who does NOT appear to be interested in identity theft or credit card fraud.
It is not clear exactly why Postal Service employees are of such interest.
The U.S. government has strongly urged the Chinese to refrain from hacking U.S. companies to steal corporate-secrets that can benefit Chinese-industries. This case appears to more closely resemble traditional Espionage; similar to the kind the United States engages in with respect to China.