What is the fine-grained topic of the following text: PEN America also reports that U.S. artist Aaron Gach was recently detained and “subjected to detailed questioning regarding an art exhibition in which he had participated in Belgium, including questions about why he was invited, who invited him, and how often he takes part in such exhibits.” CPB agents pressured Gach into turning over his cellphone, which was “removed from his sight for several minutes before being returned to him.” Gach is a U.S. citizen, but non-citizens entering the country could be subject to even more scrutiny of their electronic devices and social media accounts under a Department of Homeland Security proposal which would require them to provide their passwords as a condition of entering the country. Only return the topic.
U.S. artist Aaron Gach's detention and questioning about his art exhibition participation in Belgium, and the potential scrutiny on electronic devices for non-citizens entering the U.S. under a Department of Homeland Security proposal.