The justice department announced charges on Monday against four members of China’s military on suspicion of hacking into Equifax, the credit reporting agency, in 2017 and stealing trade secrets and the personal data of about 145 million Americans.

“This was a deliberate and sweeping intrusion into the private information of the American people,” attorney-general William P. Barr said in a statement ahead of a news conference.

Though not as large as other major breaches, the attack on Equifax was far more severe.

Hackers stole names, birth dates and Social Security numbers of millions of Americans — data that can be used to access information like medical histories and bank accounts.

“This data has economic value, and these thefts can feed China’s development of artificial intelligence tools,” Barr said in announcing the charges on Monday at the justice department.

The nine-count indictment accused the Chinese military of hacking into the company’s computer networks, maintaining unauthorised access to them and stealing sensitive, personally identifiable information about Americans.