They thought maybe he didn't understand English, but he did. So what was he doing? "Security scare closes airport concourse," from UPI, February 8:
DETROIT, Feb. 8 (UPI) -- Part of a Detroit airport terminal was shut down Monday after an Arabic man ignored instructions from security guards, police said....
The man allegedly refused to stop for questions during a security screening process, airport spokesman Michael Conway said.
Security guards at first thought the man didn't understand English and therefore didn't understand their questions, but when he was taken into custody, he began to speak in English, Conway said.
Police, who reported nothing unusual was found when the man's body was searched, were conducting a background check and planned to search his luggage and car, impounded by airport police.