In 2009, President Obama admitted that his campaign’s infrastructure had fallen victim to a hacking attack. He said that hackers had gained access to some emails, various campaign files, and policy position papers. But he didn’t attach any foreign entity to the job.

Now we know who did it. According to Michael Isikoff at NBC News, hackers from the People’s Republic of China are to blame for attacks that targeted both the Obama and McCain campaigns back in 2008.

The goal of the attacks? “To export massive amounts of internal data from both campaigns – including internal position papers and private emails of key advisers in both camps,” says NBC News.

“Based on everything I know, this was a case of political cyberespionage by the Chinese government against the two American political parties,” said Dennis Blair, President Obama’s director of national intelligence in 2009 and 2010. “They were looking for positions on China, surprises that might be rolled out by campaigns against China.”

This is the first time that we’re hearing reports on the source and gravity of the attacks. Former security officials tell NBC News that the breach was ” far more serious than has been publicly known, involving the potential compromise of a large number of internal files.”

The attack wasn’t too complicated on the surface – a simple email to staffers that contained malware. But the security team that was tapped to contain and eliminate the infection, once it was identified months later, says that is was a very sophisticated attack that replicated fast and was designed to stay hidden for a long time.

What’s interesting about the timing of this reveal is that President Obama is set to meet with Chinese President Xi Jinping this weekend at a U.S.-China summit. Reuters says that cybersecurity will be a main focus of the meeting.