An off-duty California police officer managed to slip through security at Los Angeles International Airport with a gun she unwittingly left in her hand luggage and has been detained in Taiwan.
Officer Noell Grant alerted authorities about the weapon on arrival on 13 April in Taiwan, during a layover.
She was travelling with her family to holiday in Thailand.
Lieutenant Saul Rodriguez of the Santa Monica Police Department said Ms Grant mistakenly left her personal handgun in a carry-on bag and has been barred from leaving Taiwan until the matter is resolved, although she was free to move around.
Federal officials yesterday acknowledged that proper security procedures at Los Angeles airport were clearly not respected given that Ms Grant was able to board the flight with her gun without anyone stopping her.
Nico Melendez of the Transportation Security Administration said authorities had "determined standard procedures were not followed and a police officer did in fact pass through the (airport) checkpoint with a firearm".
He added that the agency in charge of security at US airports "expects every employee to follow procedures and holds its workforce appropriately accountable".
Lieutenant Rodriguez said it was unclear whether Ms Grant would face disciplinary measures on her return to California.
"We're just working on getting her home safely right now," he said.