Far more dangerous than U-235 are the elemental products given off when nuclear fuel goes through fission—especially iodine, strontium, and cesium. “These are the things that uranium splits into when it’s working in a reactor or a bomb,” says Smith. “Those fission products are much more densely radioactive than uranium.”

Fox News senior correspondent Mike Tobin reports on IDF strikes knocking out power in parts of Tehran and Hezbollah sites in Lebanon. Israeli ambassador to the U.S. Danny Danon reacts as President Donald Trump hints at a 'regime change' in Iran.

A reactor in Tehran is a monument to the U.S. relationship with Iran when the country was led by a secular, pro-Western monarch.

Israel says it is determined to destroy Iran’s nuclear program because its archenemy’s furtive efforts to build an atomic weapon are a threat to its existence