See update below.
CBP Stops Passenger with Ballistic Armor Leading to Discovery of Weapons Cache
On August 18, a Chinese national arrived at the Detroit Metropolitan Airport from Beijing. When first encountered, the passenger gave a negative declaration to carrying any prohibited items. During an examination of the traveler’s luggage, U.S. Customs and Border Protection (CBP) Officers discovered undeclared ballistic armor and other tactical apparel.
The Chinese national appears to have been a lawful US resident from the description of his UN residence. Keep that in mind.