YUMA, Ariz. » A U.S. Army private has been charged with trying to sneak a small amount of military explosives on board a United Airlines flight from Arizona to Los Angeles, authorities said Thursday.

Pfc. Christopher Eric Wey, 19, was detained Wednesday after Transportation Security Administration screeners at the airport in Yuma found about a half-ounce of military explosives in his bags, according to a federal criminal complaint.

He was arrested and charged Thursday with attempting to carry an explosive onto an aircraft and transporting a stolen explosive, said Robbie Sherwood, a spokesman for the U.S. attorney’s office in Phoenix.

According to an FBI agent’s affidavit filed in support of the charges, Wey admitted picking up a small piece of C4 explosive that had fallen to the ground while attending a training course on explosives detection at the Army’s Yuma Proving Ground.

FBI agent Anthony Mace wrote that Wey, who was terminated from the course on Tuesday, said he planned to take the C4 explosive home and show his family, then dispose of it.

Wey made an initial appearance before a federal magistrate in Yuma on Thursday, where a federal public defender was appointed to represent him. Defense attorney Matthew Johnson declined to comment on the case, which is expected to be transferred to Phoenix.

He lives in Fort Carson, Colo., with his family, the FBI affidavit said. An Army spokesman at Fort Carson confirmed he was based there as a member of the 4th Infantry Division.

The amount of explosives was so small that if they had gone off they were unlikely to cause serious damage to a plane, but could harm nearby people.

A TSA agent at Yuma International Airport was screening checked baggage Wednesday morning when he used a swab on a large, military-style backpack with Wey’s name on it. It tested positive for explosives, and during a search a small amount of C4 was found inside a snuff tobacco can.

"Our charge is to identify explosives and keep them off airplanes, in any amount," TSA spokesman Nico Melendez said.