That effort was apparently part of an elaborate counter-intelligence operation carried out by operatives in China to find out if any of their U.S. based agents had been compromised or were under surveillance in this country.
U.S. lawmakers too have on numerous occasions voiced concerns about cyberattacks originating from China.
Despite the rising rhetoric elsewhere, the U.S. government has long stopped short of openly accusing the Chinese government of launching cyberattacks.
That restraint may finally be wearing thin after the release of the Mandiant report and the public acknowledgment of its accuracy by security experts, DoD officials, intelligence analysts and U.S. lawmakers, said Anup Ghosh, CEO and founder of security firm Invincea.
Since the report was released, "the pressure has been mounting on the [Obama] Administration to not only acknowledge the threat, but also to declare how they will defend U.S. interests against the Chinese cyberthreat," Ghosh said.
"The acknowledgement by the Pentagon is a first step in publicly declaring the threat," he said. "The administration still needs to lay out what steps it will take to both defend against the threat as well as discourage unrestrained attacks against U.S. interests."
According to the Pentagon, China's cyber espionage activities are allowing the country to collect data for intelligence and network attack purposes.
The cyberattacks are also designed to slow down incident response times and disrupt logistics, communications and commercial activities, the report warned.
The report offers little information on capabilities of other countries to launch cyberattcks on U.S. interests.
In the past, security analysts and even the government have noted that China is by no means the only nation focused on ramping up its online spying capabilities.
The U.S. is also no laggard in launching cyberattacks on other nations.
For instance the Stuxnet attacks that disabled centrifuges at Iran's nuclear facilities in Natanz in 2010 are believed to have been carried out by security experts in Israel and the United States.
A 2012 report from the U.S. Department of Defense's Defense Security Service (DSS) entities said East Asia, where China is located, and the Pacific region, accounted for 42% of all attempts to collect sensitive U.S. data illegally. That report considered a range of espionage activities, and not just cyber espionage.