Federal prosecutors are reportedly investigating if North Korea played a role in last year's theft of $81 million from a Bangladesh central bank account at the Federal Reserve Bank of New York.

The probe opens a new front in cyberwarfare where essentially a nation-state could be a suspect in a bank robbery.

No charges have been filed. Sources, who were not named in the report, told The Wall Street Journal that if charges are filed, the target would be Chinese middlemen who assisted North Korea in the heist.

North Koreans may not be charged, but North Korea would likely be implicated, these sources said. The Journal reported that some federal officials do not believe there is a North Korean connection, and the hackers could have just tweaked the code that was made public after the Sony hack.

Cyber-security experts learned that the hackers used some of the same tools in the February 2016 heist as the attackers who hacked Sony Pictures two years earlier, Bloomberg reported. The rogue nation was unhappy with the release of the movie “The interview,” and its depiction of its leader Kim Jong-un. No charges were ever filed in the Sony hack.

The hackers in the Bangladesh case reportedly used SWIFT, a global payment messaging system, and somehow persuaded the bank to transfer the money to four accounts in the Philippines.

The Journal reported that the cyberthieves used Swift access codes. Investigators believe the cyberthieves may have benefited from someone who worked at the company, The New York Times reported.

The Times reported that at first, the New York Fed released some of the $951 million in the accounts, but officials in New York halted the transfer after suspecting something was amiss.

Secretary of State Rex Tillerson recently visited Asia. North Korea was one of his most pressing topics. He said the country is a major threat and did not rule out taking pre-emptive military action.

Richard Ledgett, the deputy director of the National Security Agency, was asked about reports of the connection between cybercrimes.

“If that linkage is true, that means a nation-state is robbing banks. That is a big deal; it’s different,” he said, according to the paper at a panel discussion at the Aspen Institute. He went on to compare the situation like “security guards at Home Depot” tasked with standing up to the North Korean Army.