NARITA, Chiba Pref. (Kyodo) An American man has been arrested at Narita International Airport for carrying a loaded handgun after security staff at a U.S. airport failed to detect it, Narita airport authorities said Wednesday.

The 51-year-old man was arrested by Chiba police at Narita on Sept. 30 after airport officials found the semiautomatic in his carry-on bag while he was transferring to a flight for Bangkok, they said.

He arrived on an American Airlines flight from Dallas Fort Worth International Airport. Narita airport officials said he is a photographer but his name has been withheld.

The Narita airport authorities quoted him as saying that he placed the gun, used for competition, in the bag several years ago and mistakenly brought it with him on his travels to Asia with his family and an acquaintance.

The incident raises questions about the thoroughness of U.S. airport security, which has improved significantly since the Sept. 11, 2001, terrorist attacks on the United States. It is now rare to hear of a handgun being smuggled onto a plane leaving the U.S.

In the 9/11 attacks, two of the four jets hijacked were American Airlines planes.

In June, a passenger and an airline official managed to sneak a gun onto a plane at Philadelphia International Airport, according to U.S. media reports.

The gun was discovered by Transport Security Administration staff before the plane departed.