SALT LAKE CITY -- Federal prosecutors have leveled charges against a Utah man accusing him of spying for China.

Ron Rockwell Hansen, 58, of Syracuse, is a former Defense Intelligence Agency officer who was arrested Saturday at Seattle-Tacoma International Airport attempting to board a flight to China. The U.S. Attorney's Office for Utah accuses him of attempted espionage -- receiving hundreds of thousands of dollars for trying to transmit defense information to the People's Republic of China's Intelligence Service.

“His alleged actions are a betrayal of our nation's security and the American people and are an affront to his former intelligence community colleagues. Our intelligence professionals swear an oath to protect our country’s most closely held secrets and the National Security Division will continue to relentlessly pursue justice against those who violate this oath," said Assistant U.S. Attorney General John Demers in a statement.

Hansen made a brief appearance before a federal judge in Seattle on Monday afternoon and agreed to be returned to Salt Lake City to face espionage-related charges. The complaint out of of Utah charges Hansen with with attempting to gather or deliver national defense information to aid a foreign government. The complaint also charges Hansen with acting as an unregistered foreign agent for China, bulk cash smuggling, structuring monetary transactions, and smuggling goods from the United States.

Federal prosecutors allege that Hansen, a retired warrant officer with the U.S. Army who spoke fluent Mandarin and Russian, was hired as a DIA civilian intelligence case officer in 2006. He held a top secret clearance for years. Hansen traveled between the U.S. and China between 2013 and 2017, and provided military and intelligence information to contacts in China associated with PRCIS, the charging documents allege. He received payments of at least $800,000 originating from China, prosecutors claim.

"In addition, Hansen repeatedly attempted to regain access to classified information after he stopped working on behalf of the U.S. Government. Hansen’s alerting behavior ultimately resulted in the participation of a law enforcement source from whom Hansen solicited classified information. Hansen disclosed to the source his ongoing contact with the PRCIS, including in-person meetings with intelligence officers during his trips to China," the U.S. Attorney's Office for Utah said in a statement.

To his neighbors, Hansen was known as a friendly man who was involved in church and always with his family. They said they were shocked to learn about the allegations.

"Just known to be the guy that walks his dogs down the street, waving at everybody," Nate Cox said.

Darla Heber said she would also see Hansen and his wife walking their dog, and that she mainly knew Hansen through him teaching Sunday school. She said she couldn't comprehend what she was hearing.

"Terrible," she said. "It's terrible, and it’s hard to imagine."

Heber said she didn't know what Hansen did for a job, and wasn't aware of his military background. She indicated that she knew his job required many out-of-town trips.

"I never knew when he was going or coming back," Heber said. "He traveled quite a bit I was told, for his job."

Heber and other neighbors told Fox 13 they wondered if the allegations were part of some misunderstanding or mistake.

"I keep hoping they find they've made a mistake or an error," she said, adding, "but on the other side I imagine to take it this far-- they must feel they have good grounds,."

Read the complaint filed in federal court here: