Four members of the Chinese military have been charged with breaking into the networks of the Equifax credit reporting agency and stealing the personal information of tens of millions of Americans.

The 2017 breach affected roughly 145 million people, with the hackers successfully stealing names, Social Security numbers and other personal information stored in the company's databases.

The Justice Department on Monday blamed China for one of the largest hacks in history.

The four - Wu Zhiyong, Wang Qian, Xu Ke and Liu Lei - are members of the People's Liberation Army, which is an arm of the Chinese military. They remain at large.

Members of the People's Liberation Army Wang Qian (left) and Wu Zhiyong (right) are among four Chinese servicemen who have been charged with hacking Equifax

Xu Ke (left) and Liu Lei (no photo available, right) are among the four people suspected of stealing personal data belonging to 145 million Americans in 2017

Attorney General William Barr on Monday announced the charges against the four Chinese military men in connection to the Equifax data breach

They are also accused of stealing the company's trade secrets.

'This was a deliberate and sweeping intrusion into the private information of the American people,' Attorney General William Barr said at a press conference announcing the charges on Monday.

'Today, we hold PLA hackers accountable for their criminal actions, and we remind the Chinese government that we have the capability to remove the Internet's cloak of anonymity and find the hackers that nation repeatedly deploys against us.'

The criminal charges were filed in federal court in Atlanta where the company is based.

Barr said the hackers spent weeks in the Equifax system, breaking into computer networks, stealing company secrets and personal data.

According to the indictment, the four member of the People Liberation Army's 54th Research Institute 'exploited a vulnerability in the Apache Struts Web Framework software used by Equifax’s online dispute portal. They used this access to conduct reconnaissance of Equifax’s online dispute portal and to obtain login credentials that could be used to further navigate Equifax’s network.

'The defendants spent several weeks running queries to identify Equifax’s database structure and searching for sensitive, personally identifiable information within Equifax’s system. Once they accessed files of interest, the conspirators then stored the stolen information in temporary output files, compressed and divided the files, and ultimately were able to download and exfiltrate the data from Equifax’s network to computers outside the United States.

'In total, the attackers ran approximately 9,000 queries on Equifax’s system, obtaining names, birth dates and social security numbers for nearly half of all American citizens.'

To avoid detection, the hackers routed traffic through 34 servers located in 20 countries 'to obfuscate their true location.'

'This was an organized and remarkably brazen criminal heist of sensitive information of nearly half of all Americans, as well as the hard work and intellectual property of an American company, by a unit of the Chinese military,' Barr said.

The 2017 breach affected roughly 145 million people, with the hackers successfully stealing names, Social Security numbers and other personal information stored in the company's databases

The hackers also used encrypted communication channels within Equifax's network to blend in with normal network activity and deleted compressed files and wiped log files on a daily basis in an effort to eliminate records of their activity.

FBI Deputy Director David Bowdich said there was no evidence yet of the Equifax data having been used, for example to hijack a person's bank account or credit card.

But he added: 'If you get the personal identifying information of people, you can do a lot with that.'

The January 28 indictment includes charges of conspiracy to commit computer fraud, conspiracy to commit economic espionage and conspiracy to commit wire fraud.

The scandal sent Equifax into turmoil, leading to the exit of its then-CEO, Richard Smith, and multiple congressional hearings as the company’s slowness to disclose the breach and security practices were challenged by lawmakers.

Equifax ultimately agreed to pay up to $700million to settle claims it broke the law during the data breach and to repay harmed consumers.

FBI Deputy Director David Bowdich (center) said there was no evidence yet of the Equifax data having been used to hijack a user's credit card or bank account

In a statement released on Monday, Equifax CEO Mark Begor praised the Justice Department and FBI for their 'tireless efforts' in pursuing those responsible for the cyberattack.

'It is reassuring that our federal law enforcement agencies treat cybercrime – especially state-sponsored crime – with the seriousness it deserves, and that the Justice Department is committed to pursuing those who target U.S. consumers, businesses and our government,' Begor said.

'The attack on Equifax was an attack on US consumers as well as the United States.'

The case comes as the Trump administration has warned against what it sees as the growing political and economic influence of China and efforts by Beijing to collect data on Americans and steal scientific research and innovation.

The case is one of several the Justice Department has brought over the years against members of the PLA.

The Obama administration in 2014 charged five Chinese military hackers with breaking into the networks of major American corporations to siphon trade secrets.

If the previous cases are any indication, there is little to no chance the accused perpetrators of the sweeping Equifax breach would ever be brought to justice by US authorities because the US does not have an extradition agreement with China.