A man is due in court on Friday after he was arrested at a US airport with a smoke grenade, gas mask and body bags in his luggage.
Boston-bound Yongda Huang Harris, 28, was arrested at Los Angeles Airport on suspicion of transporting hazardous materials on a flight from Japan.
Harris, a US citizen who works in the Far East, faces up to five years in prison if convicted.
A detention hearing is scheduled for Friday to decide if Harris is a likely flight risk or a danger to the public.
US Customs and Border Protection officers became suspicious last Friday when they noticed he was wearing a bulletproof vest and flame-retardant trousers under his trenchcoat.
They called in Homeland Security special agents who carried out a search of his luggage.
They found numerous suspicious items including knives, body bags, a hatchet, a collapsible baton, a biohazard suit, a full-face respirator, billy clubs, handcuffs, leg irons and a device to repel dogs.
The smoke grenade was later X-rayed by the Los Angeles Police Department's bomb squad.
Most of the items do not violate Transportation Security Administration guidelines for what is permissible in checked luggage, and the protective vest and trousers are not listed among items prohibited on flights.
Harris' motives remain unclear, partly because he has refused to cooperate with federal authorities.
