Security concerns are rising in the U.S. and Europe after reports that Iran may activate sleeper cells following the death of Ali Khamenei and the rise of Mojtaba Khamenei. U.S. President Donald Trump said authorities are monitoring potential threats after intelligence agencies reportedly intercepted encrypted messages linked to Iranian operatives. The warnings come as security is tightened in major U.S. cities and across Europe following recent incidents, including a synagogue blast in Belgium and an explosion near the U.S. Embassy in Oslo, amid fears the Middle East war could spill over globally.