CTP’s Threat Update series is a weekly update and assessment of Iran and the al Qaeda network. CTP’s Iran team follows developments on the internal politics, nuclear negotiations, and regional conflicts closely. The al Qaeda network update includes detailed assessments of al Qaeda’s affiliates in Yemen, the Horn of Africa, and the Maghreb and Sahel. Below are the top three takeaways from the week: 1. Pro-ISIS groups are expanding operations into eastern Yemen, where AQAP has traditionally had a dominant naval presence. 2. IRGC naval forces detained the Maersk Tigris in the Strait of Hormuz on April 28 based on a lawsuit filed by Iranian oil company Pars Talaei against Danish shipping group Maersk. 3. Rebel violence is increasing in northen Mali as Tuareg rebels attacked a town near the Mauritanian border.