The Chinese government hacked a Navy contractor's computers earlier this year, stealing huge amounts of very sensitive data — including secret plans to develop a supersonic anti-ship missile for use on U.S. submarines by 2020, The Washington Post disclosed Friday.
The breach occurred in January and February, targeting "highly sensitive" information kept on the contractor's unclassified computer system, the officials told the Post.
The contractor, which was not named, works for the Naval Undersea Warfare Center in Newport, R.I., which conducts research and development for submarines and underwater weapons.
The officials spoke to the Post "on the condition of anonymity to discuss an ongoing investigation."
The Navy and FBI are investigating the breach. The Pentagon's Damage Assessment Management Office is also involved. Defense Secretary James Mattis' office declined to comment.
"There are measures in place that require companies to notify the government when a 'cyber incident' has occurred that has actual or potential adverse effects on their networks that contain controlled unclassified information," Navy spokesman Cmdr. Bill Speaks told the Post.
"It would be inappropriate to discuss further details at this time," he said.
According to the report, 614 gigabytes of material was taken on a secret project known as "Sea Dragon" — and the Navy submarine development unit's electronic warfare library was compromised.
The Post "agreed to withhold certain details about the compromised missile project at the request of the Navy, which argued that their release could harm national security."
The breach continues China's longstanding effort to "blunt the U.S. advantage in military technology and become the pre-eminent power in east Asia," the Post reported.
It also comes as President Donald Trump continues to court Beijing in his efforts to denuclearize North Korea.
Investigators told the Post that the Chinese Ministry of State Security, a civilian spy agency, carried out the hack.
Staffers worked out of an MSS division in Guangdong Province, where a major foreign hacking operation is located.
Peter Mattis, a former analyst in the CIA counterintelligence center, told the Post that the MSS hackers are more skilled and much better at covering their tracks.
The MSS, he said, hacks all forms of intelligence: foreign, military and commercial.
According to the Post, the Sea Dragon project was created by the Pentagon in 2012 to adapt existing U.S. military technologies to new applications.
The Defense Department has disclosed little about Sea Dragon other than to say that it will introduce a "disruptive offensive capability" by "integrating an existing weapon system with an existing Navy platform."
The Pentagon has requested or used more than $300 million for the project since late 2015, with underwater testing scheduled to begin by September.
Military experts said the breach signaled that China could be working to complicate the Navy's ability to defend U.S. allies in Asia amid a conflict with Beijing in the region.
"U.S. naval forces are going to have a really hard time operating in that area, except for submarines, because the Chinese don't have a lot of anti-submarine warfare capability," Bryan Clark, a naval analyst at the Center for Strategic and Budgetary Assessments, told the Post.
"The idea is that we are going to rely heavily on submarines in the early effort of any conflict with the Chinese."