https://cdnph.upi.com/ph/st/th/7371784468010/2026/upi/c72fec1aa2eda73a1cc0fbb0edf071b2/v1.5/Iran-says-US-strikes-hit-nuclear-power-plant-UN-investigates.jpg" /> The United Nations' nuclear energy agency said Sunday it's investigating Iran's allegation that the U.S. military struck a nuclear power plant.