According to reports a new hack attack on the U.S. Office of Personnel Management has investigators are looking for a link to China.

This time, the hack targeting the records of millions of security-clearance holders – that means CIA operatives, NSA spooks, and military special ops potentially compromised. The report says authorities believe hackers accessed a key form – also listing contacts and relatives, and details of cohabitants that include their social security numbers.

The breach follows on the heels of one of the biggest known attacks on U.S. federal networks last month. The White House saying the records of up to four million workers had been stolen.

Other sources put the number much higher – up to 14 million people. China denies it had anything to do with the attack.

Analysts say Chinese hackers are building massive databases that could be used for traditional espionage like recruiting spies or unmasking covert operatives in the field.