The U.S.B-2 stealth bomber is the only aircraft capable of carrying and dropping 'bunker busters," the world's most powerful nonnuclear bomb. Here's what we know about the 30,000-pound weapons and why the US is using them to strike nuclear sites in Iran.

President Donald Trump’s order to bomb Iran’s nuclear facilities presents a new test of the Constitution and the extent of presidential powers to conduct war despite a lack of congressional approval.