Google is being aided by officials at the National Security Agency in the search giant's investigation of the cyber attacks that so upset the company last month.
A Google spokeswoman declined to comment, and the NSA didn't immediately respond to requests for comment.
The partnership began weeks ago, as the Internet company shared details about the attack – which it said it believed originated in China and affected more than 20 companies – with various government agencies.
In response, Google said it would stop censoring its search results in China – a move it has yet to take as it continues discussions with Chinese officials about how it can continue to operate in the country. In recent weeks, Google's chief executive Eric Schmidt has said the Internet company doesn't want to back out of China but wants to be there on "different terms."
Companies have been more reluctant to work with the NSA in the wake of the debate over domestic surveillance in Washington because they fear being seen as aiding intelligence agencies in a way that would undermine the trust of customers. Addressing this private-sector anxiety is one of the largest challenges facing the White House's new cyber chief Howard Schmidt.
NSA officials had only heard rumors about the Google attack until the company announced it publicly, said one person familiar with the investigation.
For more on Google and the NSA, read the full story in the Wall Street Journal.