Hackers broke into a US Government database, possibly accessing the personal data of millions of current and former federal employees.  Investigators are probing whether the culprits were based in Shanghai, as part of the Chinese military’s cyber warfare unit.

“The ramifications are very serious,” said US Senate Susan Collins of Maine to America’s NBC News.  The high-ranking member of the Senate Intelligence Committee continued, Potentially 4 million former and current federal employees have had their information compromised, and because OPM is the agencies that holds security clearances, that's giving a potential enemy like China very valuable information.”

OPM stands for the Office of Personnel Management, the official agency that vets and hires federal workers.  It also approves security clearances for 90 percent of the federal government.  Although it could be the biggest hack in US history, potentially affecting every agency of the U.S. government, so far officials say it does not appear to be a “worst-case scenario” – that the hackers didn’t find the identities and locations of covert CIA and other operatives.

The Obama administration and the intelligence community are scrambling to find out exactly how far this hack went.  Because names, social security numbers, and birthdates were part of the pilfered information, federal workers are urged to check their bank accounts and credit ratings to make sure they’re not getting ripped off.