The United States claimed that Chinese hackers broke into the networks of the US office of personnel management in order to access the files of all federal employees who had applied for top-secret security clearances. According to senior US officials, the Chinese obtained access to the agency’s databases four months ago before being detected and blocked. However, nothing is said about the damage done.

It is known that accusations of hacking by China and counterclaims of such activity by the government of the United States have strained the relations between the two counties. Chinese hacking was discusses by the representatives of both sides in Beijing, though they have publicly steered clear of the controversy.

Two months ago, the US Justice Department filed an indictment against 5 Chinese military officials who were alleged of operating under hacker aliases and penetrating computer networks of several steel companies and solar and nuclear technology makers. China has denied all allegations.

The US Office of Personnel Management houses personal details of all federal employees. The individuals applying for security clearances have to provide such information as foreign contacts, previous jobs, past drug use and other details. Media reports say that the attack had been traced to China, but that it is unknown whether the government was involved. According to Homeland Security Department, an attack did occur, but no loss of personal details had been identified.

The hacker attack took place in March, but wasn’t announced, even though the Obama administration has urged American companies to tell the government and the consumers about breaches in security. The representative for the administration explained that they have never advocated that all intrusions be made public, but rather that targeted businesses notify their customers if the intruder had access to consumers’ personal details. In addition, the Obama administration has also advocated that organizations voluntarily share information about intrusions. In this case, the administration admitted that it had no reason to believe that personally identifiable information for federal employees had been compromised by the hackers.