A Chinese businessman has pleaded guilty to conspiring to hack into the computer systems of U.S. defence contractors, including Boeing, to steal data on military projects, according to court records released Wednesday.

Su Bin, 50, admitted to conspiring with two unnamed hackers in China to export U.S. military information to the communist nation between 2008 and 2014, according to a plea agreement reached in federal California court on Tuesday.

The U.S. Department of Justice said Su Bin and two other conspirators are alleged to have accessed the computer networks of U.S. defense contractors without authorization and stolen data related to military aircraft and weapons systems. This image shows a page of the flight test plan for the F-35, which the FBI says is possibly the world's most advanced multi-role fighter aircraft, from an internal company document that Su Bin allegedly acquired and edited — adding translation — before passing it back to contacts in China. (U.S. criminal court complaint June 27, 2014)

Su was arrested in Richmond in the summer of 2014, and extradited to the U.S. in February. He is a Chinese citizen and permanent resident of Canada.

The men targeted fighter jets such as the F-22 and the F-35, as well as Boeing's C-17 military cargo aircraft program, according to court papers.

Su's attorney, Robert Anello, declined to discuss the case in detail except to say that Su is "hopeful to move on with his life."

Su, described by prosecutors as a China-based businessman in the aviation and aerospace fields, faces up to five years in federal prison at his sentencing July 13. He had faced 30 years before reaching the plea agreement with prosecutors.

As part of the conspiracy, prosecutors say Su would email the hackers in China explaining what people, companies and technology to target. Once data was stolen, prosecutors say Su would translate it from English to Chinese, and email the value of the information to those who benefited from its theft.

U.S. Attorney Eileen Decker said in a statement Wednesday that cybercrime is one of the most serious national security threats.

Su's "guilty plea and conviction demonstrate that these criminals can be held accountable no matter where they are located in the world and that we are deeply committed to protecting our sensitive data in order to keep our nation safe."

Cybersecurity has become an increasingly sore point in U.S.-China relations. A report by the U.S.-China Economic and Security Review Commission last year found that China's increasing use of cyber espionage has already cost U.S. companies tens of billions of dollars in lost sales and expenses in repairing the damage from hacking.

In many cases, the report says stolen trade secrets have been turned over to Chinese government-owned companies.

"The United States is ill-prepared to defend itself from cyber espionage when its adversary is determined, centrally co-ordinated,and technically sophisticated, as is the CCP and China's government," according to the report, referring to the ruling Chinese Communist Party.