The Justice Department on Tuesday unsealed charges against 10 Chinese intelligence officers accusing them of a relentless campaign to hack into several United States aviation companies and steal corporate secrets over the last five years.

“For the third time since only September, the National Security Division, with its U.S. Attorney partners, has brought charges against Chinese intelligence officers from the JSSD and those working at their direction and control for stealing American intellectual property,” said John Demers, assistant attorney general for national security.

“This is just the beginning," he added.

JSSD stands for the Jiangsu Province Ministry of State Security, which is a foreign intelligence arm of China’s Ministry of State Security, the government’s agency responsible for intelligence and political security.

The “ultimate goal” by the conspirators was to steal data, intellectual property, and confidential business information, said the Justice Department.

Two of the people charged were intelligence officers who worked from 2010 to 2015 to steal turbofan engine technology used in commercial airplanes.

The Justice Department said the other six defendants are alleged hackers working at the direction of the intelligence officers.

Two other defendants were employed in a French aerospace company’s office in Suzhou, China, infecting one of the company’s computers with malware at the direction of the security officers.

Earlier this month, the Justice Department announced a Chinese government spy was lured by FBI agents to Belgium, where he was extradited to the U.S. to be prosecuted for economic espionage charges.

And in September, federal officials alleged that an electrical engineer working on behalf of Chinese intelligence officials enlisted in the U.S. Army Reserves and sought to target other potential defense industry sources.