LOS ANGELES -- In an age when air travelers grudgingly surrender bottled water at security checkpoints, the most striking aspect of the arrest of a passenger wearing a bulletproof vest and flying with luggage stocked with knives, clubs and body bags is that virtually all of it was permissible to have onboard.
Yongda Huang Harris, 28, was taken into custody at Los Angeles International Airport last week during a stopover on a trip from Japan, when U.S. Customs and Border Protection officers noticed he was wearing the bulletproof vest under his trench coat, along with flame-retardant pants and knee pads.
By then, he had reached the U.S. after a stop in South Korea with a suspicious array of knives and other weaponry in his checked luggage, including a smoke grenade, a hatchet, a biohazard suit, a collapsible baton, masks, duct tape, leg irons and plastic restraints, authorities say.
Most of the items _ including the hatchet and knives _ wouldn't violate Transportation Security Administration guidelines for what is permissible in checked luggage, and the protective vest and pants are not listed among items prohibited on flights.
The smoke grenade was X-rayed by police bomb squad officers in Los Angeles, who said the device fell into a category that is prohibited on board passenger aircraft.
But in Incheon, South Korea, where Harris deplaned and went through security before boarding a Los Angeles-bound flight, items such as axes, knives or smoke-generating cartridges are allowed in checked bags, according to a senior airport security official who spoke on condition of anonymity because he wasn't authorized to speak to media.
The official said Harris' checked luggage went through X-ray scans at Incheon but no hazardous materials were found and that no red flags were raised about its contents because the items did not violate that nation's guidelines for checked luggage.
Rules, or the lack of them, that govern what passengers can do, carry or wear on flights can seem alternately reasonable or unfathomable, sometimes even bizarre.
Increased airline security after 9/11 sought to armor flights against terrorist threats, but they can also test credulity for those getting on board.
An intrusive pat-down by security or the discovery of a too-big bottle of tanning lotion can leave a passenger feeling violated, while Harris appears to have triggered no alarm before arriving in Los Angeles.
"The one thing that concerns me is he was able to board a plane internationally with all these weapons and whatnot, and nobody in Japan, nobody in Korea, bothered to find these things until he got to America," said Gadisa Goso, 29, a school administrator and neighbor of Harris' mother in Boston. "That's a big concern for, like, for the U.S."
Michael Cintron of the International Airline Passengers Association said rules for passengers "can get very confusing, and it can get complex, and it can get disconcerting.
"For the average passenger, you see someone getting stopped for liquid, an innocuous object, then you hear about stories like this," Cintron said.
A U.S. Homeland Security official briefed on the investigation said Wednesday that South Korean security officials screened Harris and his carry-on luggage before he got on the Los Angeles flight, but the smoke grenade somehow made it onto the plane in his checked luggage. The official was not authorized to discuss the case publicly and spoke on condition of anonymity.
Harris is not cooperating with federal officials who are trying to determine why he was headed to Boston with the cache of weapons, authorities said.
Tom Blank, a former deputy administrator at the TSA, said the U.S. will likely look at whether the failure to detect the grenade on a U.S.-bound jet was a one-time lapse or part of a wider security vulnerability.
If the U.S. determines a country's airport doesn't meet U.S. standards, it can ask for stronger security measures and even prohibit flights from flying directly to the U.S. from that country.
"This clearly looks like an error. Something slipped through that should not have slipped through," Blank said of the grenade.
There is no indication that Harris, who does not have a criminal record, is linked to a terrorist organization or planned to damage the plane, and it's not likely a smoke grenade could bring down the aircraft, the federal official said.
But the smoke grenade is banned from planes under the United Nations' explosives shipping rules. Depending on the conditions when it is ignited, the grenade could fill the cabin with smoke or cause a fire, officials said.
Asked about the grenade, the Korean airport security official pointed out that South Korean guidelines list as legal non-flammable, inert cartridges or tins that produce smoke, but said he would have to see the specific item before he could say more.
Customs officers also believed that the lead-filled, leather-coated billy clubs and collapsible baton might be prohibited by California law, according to an affidavit filed in U.S. District Court.
Harris has been charged with one count of transporting hazardous materials, an offense that carries a maximum penalty of five years in prison. He made a brief court appearance Tuesday but his arraignment was delayed until Friday and he was ordered held until then.
Harris is a U.S. citizen whose permanent residence is in Boston, though he recently started living and working in Japan, officials said.
Attempts to reach Harris' family in Boston were unsuccessful. His attorney, Steven Seiden, was unavailable, said spokesman Chris Williams, who described Harris as very intelligent, earning A's in high school and college calculus.
Williams objected to characterizations that Harris was not cooperating with authorities, saying he followed his attorney's advice to exercise his constitutional right to remain silent.
"He has that right. He is an American citizen," Williams said Wednesday.
Harris graduated from Boston University's Metropolitan College in January 2011 with a bachelor of science in biomedical laboratory and clinical sciences, said Constance Phillips, the program director. She called Harris a shy, good student who completed several internships performing research at well-known labs in the Boston area.
Harris traveled from Kansai, in western Japan, to Incheon before landing in Los Angeles. South Korean officials said he traveled on all Asiana Airlines flights, though the airline declined to confirm that, citing South Korean law banning disclosure of passengers' information without their consent.
Security at Japanese airports is similar to security in the U.S. Metal detectors and X-rays screen every person and every bag, both checked and carry-on. Airport and immigration officials at Kansai International Airport said Wednesday that airlines are primarily responsible for luggage inspection, but no problematic cases have been reported recently.
An immigration officer at Kansai, Masahiro Nakamoto, said authorities did not report anything suspicious at the time Harris boarded, but arriving passengers are checked more closely than those leaving the country. Spokesman Keisuke Hamatani said Kansai security officials had not reported any suitcases containing the hazardous materials U.S. authorities say they found in Harris' luggage.
Yasunori Oshima, an official at Japan's Land and Transport Ministry's aviation safety department, said there had been no official inquiry or request from U.S. authorities to look into the case, which he said would have been more of a concern if the hazardous materials were brought into the cabin rather than checked.
"The case does not seem to pose any immediate concerns about aviation security measures in Japan," he said.
Airport police said they do not believe the case constitutes illegal conduct under the Japanese domestic criminal code, but Japan may cooperate at the request of U.S. investigators.
Sullivan reported from Washington. Contributing to this report were Associated Press writers Shaya Tayefe Mohajer in Los Angeles, Elliot Spagat in San Diego, Rodrique Ngowi in Boston, Erika Niedowski in Providence, R.I., Eric Talmadge and Mari Yamaguchi in Tokyo, Alicia A. Caldwell in Washington, and Hyung-jin Kim in Seoul.