Iran has arrested another American holding dual citizenship, bringing to four the number of Iranian Americans imprisoned in Tehran after they came under suspicion by hard-line security forces.

Siamak Namazi, a businessman based in Dubai who is in his early 40s, was arrested earlier this month when he was visiting a friend in Tehran, according to a family friend who did not want to be identified. It was not clear whether any charges have been brought against him or what authorities might allege he did.

Read full story at The Washington Post.