An American-Iranian has become the fourth Western citizen with dual Iranian citizenship to have been arrested in Iran in the past five months, The Washington Post reported on Wednesday.

Reza “Robin” Shahini traveled to Iran in May to visit his sick mother. Before he left, he deleted any references on social media that he thought would attract the attention of Iranian authorities. Nonetheless, he was arrested on July 11 for committing unspecified crimes against the Islamic Republic.

There are at least six other dual citizens from the U.S., UK, France, and Canada currently known to be held in Iran—three of whom have been arrested since February (one, Baquer Namazi, had come to Iran to try to free his son Siamak, who has been detained since October). The situation reflects, as Reuters described, “the highest number of Iranians with dual-nationality detained at one time in recent years to have been acknowledged.”

The United Kingdom upgraded its travel advisory to Iran last week, warning that “British nationals – including dual British/Iranian nationals – face greater risks than nationals of many other countries.” The advisory added that students and independent travelers faced a higher risk of arbitrary arrest.

In Why Does Iran Keep Taking American Hostages?, published in the September 2015 issue of The Tower Magazine, Iran expert Ali Alfoneh described the regime’s detainment of foreign and dual-nationals as “a perfectly normal procedure and political practice in the Islamic Republic. That has been the case since the first day of the revolution and continues until today.”

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