Transcript for No official explanation why Navy vet being held in Iran

There is word tonight that a U.S. Navy veteran is being held prisoner in Iran. The man's mother just learning the news back here in the U.S. After he failed to return home from a visit to Iran in July. ABC's chief global affairs correspondent with us live tonight. Martha, do we know why Iran may have taken him prisoner? Reporter: David, tonight, there is no official explanation why Michael white, a 46-year-old Navy veteran from California, is imprisoned in Iran. He went missing six months ago. His mother filing a missing persons report. But only learning he was in prison a few weeks ago. The state department does warn Americans not to travel to Iran, citing a very high risk of arbitrary arrest of U.S. Citizens. White's mother told ABC it was last July, just two months after president trump withdrew from the nuclear agreement, that her son traveled to Iran to see his Iranian girlfriend, which he had done before. The state department now telling her there is no indication of when or if he will be released. David? All right, our chief global affairs correspondent Martha Raddatz tonight. Martha, thank you.

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