A Chinese citizen living in Vancouver who admitted helping Chinese military officers hack into the computer networks of U.S. defence contractors to steal classified information has been sentenced to 46 months in prison.

Su Bin, a 51-year-old multimillionaire businessman working in aviation, was convicted of participating in a years-long conspiracy to steal military technical data, including schematics related to Boeing's C-17 military transport plane as well as F-22s and F-35s.

According to a plea agreement released by U.S. prosecutors, Mr. Su admitted that he acted as a data scout to access sensitive military data on servers for U.S. defence contractors and sent relevant information to China. He said he was motivated by the prospect of "commercial advantage and private financial gain."

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In addition to the prison term, Mr. Su was ordered to pay a $10,000 (U.S.) fine by a District Court judge in Los Angeles for his part in the criminal hacking conspiracy, which took place from October, 2008, to March, 2014, while he resided in Canada with his family and took frequent trips across the border. In August, 2012, he bought a $2-million home in Richmond, B.C., with his wife.

"Su Bin's sentence is a just punishment for his admitted role in a conspiracy with hackers from the People's Liberation Army Air Force to illegally access and steal sensitive U.S. military information," John Carlin, the assistant attorney-general for U.S. National Security, said in a statement.

The statement also details how Mr. Su, who ran his China-based company Lode-Tech from Vancouver, worked with military officers in China to steal information from U.S. defence contractors, highlighting which files to steal and why the information was important, often translating them before sending them to China.

The sentencing is the first time the U.S. Department of Justice has highlighted allegations that Mr. Su and two co-conspirators e-mailed reports addressed to the headquarters for the Chinese People's Liberation Army, previously reported by The Globe and Mail in February.

Adam Segal, director of the digital and cyberspace policy program at the Council on Foreign Relations, believes that the move fits a larger trend of the United States being more willing to attribute attacks to specific actors as a message to foreign agencies.

"I think part of that has to do with trying to convince not only China, but also Iran and North Korea and others, that the U.S. is getting better at attribution, and that attackers should not expect to remain unknown and anonymous," he said.

The Globe also revealed that court filings in Canada described the co-conspirators as "Chinese military officers" who sent Mr. Su pictures of themselves with identifiable names and ranks. U.S. prosecutors have not charged or publicly identified these individuals.

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Charges against Mr. Su were first announced in 2014, leading to his arrest in Canada on a U.S. warrant. He ultimately waived extradition to the United States, where he pleaded guilty to one count of conspiring to gain unauthorized access to a protected computer and to violate the Arms Export Control Act. As part of his plea deal, he negotiated a maximum five-year prison sentence with prosecutors.

When Mr. Su went to the United States, Canadian immigration authorities withdrew a bid launched to revoke his permanent resident status. Government officials could not be reached for comment on whether he will be authorized to return to Canada at the conclusion of his U.S. prison term.

Earlier this year, the Chinese government denied claims that a Canadian man detained in China was charged with espionage as retribution for proceedings against Mr. Su. Kevin Garratt and his wife, Julia, were arrested near the North Korean border, where they ran a coffee shop and did humanitarian work, weeks after Mr. Su's arrest in Vancouver. Ms. Garratt was released on bail in February, 2015, but has been barred from leaving the country or speaking to the media.

The Chinese government has repeatedly denied any involvement in hacking, but Mr. Su's cyber-espionage efforts have been lauded by state-controlled media in China.

"On the secret battlefield without gunpowder, China needs special agents to gather secrets from the U.S. As for Su, be he recruited by the Chinese government or driven by economic benefits, we should give him credit for what he is doing for the country," said a March editorial in the Global Times, a publication with significant ties to the ruling Communist Party.

The editorial was headlined: "Su Bin deserves respect whether guilty or innocent."

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With reports from Colin Freeze and Nathan VanderKlippe