WASHINGTON — China has stolen sensitive data related to naval warfare from the computers of a Navy contractor, American officials said on Friday, in another step in the long-running cyberwar between two global adversaries.
The breach occurred this year, the officials said, when Chinese government hackers infiltrated the computers of a company working on a Navy submarine and underwater programs contract. The company, which was not identified, was doing work for the Naval Undersea Warfare Center, which is based in Newport, R.I.
Officials said that the data gleaned by China was unclassified.
Navy officials declined to speak publicly about the hack, which was first reported by The Washington Post.
But in a statement, Lt. Marycate Walsh, a Navy spokeswoman, cited “measures in place that require companies to notify the government when a cyberincident has occurred that has actual or potential adverse effects on their networks that contain controlled unclassified information.”
She said it would be “inappropriate to discuss further details at this time.”
China and the United States have been locked in an escalating fight over cyber and military technology, with Beijing making rapid gains in recent years. American officials — from both the Trump administration and the Obama administration before it — concede that Washington has struggled to deter Chinese hacking, and have predicted the cyberattacks will increase until the United States finds a way to curb them.
The theft of the Navy system is hardly the largest, or the most sensitive, of the designs and systems stolen by Chinese hackers over the years. But it underscores a lesson the American government keeps learning: No matter how fast the government moves to shore up it cyberdefenses, and those of the defense industrial base, the cyberattackers move faster.
The plans for the F-35, the nation’s most expensive fighter jet in history, were taken more than a decade ago, and the Chinese model looks like an almost exact replica of its American inspiration.
A People’s Liberation Army unit, known as Unit 61398, was filled with skilled hackers who purloined corporate trade secrets to benefit Chinese state-owned industry. But many of its targets were defense related as well. Members of the unit were indicted in the last two years of the Obama administration, but none are likely to come back to the United States to stand trial.
The most sophisticated hack of American data took place at the Office of Personnel Management. It lost the files of about 21.5 million Americans who had filed extensive questionnaires for their security clearances. The forms listed far more than Social Security numbers and birth dates. They detailed medical and financial histories; past relationships; and details about children, parents and friends, particularly non-United States citizens.
The office stored much of the data at the Interior Department and encrypted nearly none of it. So when the Chinese copied it in a highly sophisticated operation, they were prepared to use big data techniques to draw a map of the American elite, who worked on which projects and who knew whom. The loss was so severe that many American intelligence agencies canceled the deployment of new officers to China.
But the United States is unlikely to retaliate. To most intelligence officials this is just another espionage case, bearing similarities to what the United States does around the world.
Lieutenant Walsh said that the Navy treated “the broader intrusion against our contractors very seriously.”
“If such an intrusion were to occur, the appropriate parties would be looking at the specific incident, taking measures to protect current info, and mitigating the impacts that might result from any information that might have been compromised,” she said.
The United States and China are wrangling over trade issues but also jointly looking to rein in North Korea’s nuclear ambitions. President Trump is headed to Singapore this weekend for a June 12 summit meeting with North Korea’s leader, Kim Jong-un.
The United States and China are also tangling over Beijing’s militarization of disputed islands in the South China Sea.
Last week, Defense Secretary Jim Mattis harshly criticized the Chinese government for continuing to militarize a string of islands in the South China Sea, calling the presence of advanced military equipment and missiles there a flagrant show of military power.
To add muscle to American complaints, Mr. Mattis recently disinvited the Chinese military from a large, multinational naval exercise this summer — in part because of the anti-ship and surface-to-air missiles, and other weapons, that China has positioned on the Spratly Islands.
A United States official, speaking on the condition of anonymity because he was not allowed to be identified in discussing the issue, said the Navy was investigating the breach with the help of the F.B.I.
David E. Sanger contributed reporting.