An American citizen admitted to working on behalf of Chinese intelligence operatives for years, helping gather information on U.S. targets and attempting to penetrate American political circles, according to federal authorities.Thomas Weir Pauken II, 50, pleaded guilty Thursday to acting inside the U.S. as an agent of the People's Republic of China without notifying the attorney general, the Department of Justice announced.The guilty plea prompted a stark warning from the FBI, which said the case demonstrates how far the Chinese Communist Party is willing to go to collect intelligence and influence activities inside the U.S."By his own admission, not only did Thomas Pauken attempt to infiltrate U.S. political circles at the direction of China's Ministry of State Security, but he gathered intelligence on his American targets and reported it back to his Chinese intelligence handlers," FBI Assistant Director Roman Rozhavsky said.CALIFORNIA MAYOR ACCUSED OF SECRETLY WORKING FOR CHINA, SPREADING PROPAGANDA WHILE IN OFFICE: FEDSFederal prosecutors said Pauken maintained relationships with multiple China-based contacts who tasked him with identifying and cultivating people in the United States capable of providing information of interest to Chinese intelligence services.According to court filings, Pauken acted as an intermediary between those contacts and individuals in the U.S., facilitating communications and relaying information gathered from his targets.Authorities allege he was compensated more than $100,000 for his efforts and made repeated trips from China to the U.S. over several years as part of the operation.CHINA'S SPYING IN CUBA SPARKS ALARM ON CAPITOL HILL AFTER FRESH SATELLITE IMAGES SHOW SURVEILLANCE BUILDUPProsecutors also said Pauken prepared research and reporting for other China-based contacts he believed were connected to the Chinese government.In addition, investigators said he provided information to a group based in Wuhan that sought insights into American technology and the Justice Department and was interested in locating expertise that could support cyber operations.HOW CHINA'S CYBERESPIONAGE HAS CHANGEDRozhavsky said the case serves as a reminder that foreign intelligence services continue to target American institutions."This case illustrates the lengths to which the Chinese Communist Party will go to undermine our democratic institutions and degrade our political freedoms, but it also demonstrates the FBI’s resolve to defend the homeland from threats to our national security," he said. "Let this plea serve as a clear warning: If you attempt to help a foreign adversary as an unregistered agent in the U.S., the FBI will find you and bring you to justice."Pauken is scheduled to be sentenced Sept. 1. He faces a maximum penalty of 10 years in federal prison, though his final sentence will be determined by a judge.The case was investigated by the FBI's Philadelphia and Washington field offices.