The U.S. and Israel began "major combat operations" in Iran overnight with the aim of destroying the country's military capabilities and fostering regime change, President Trump announced.The big picture: Iran is certain to retaliate, and some U.S. officials have been worried about entering into such a conflict without a clear sense of how it will end. Driving the news: In a video statement, Trump accused Iran of conducting "mass terror" ever since the 1979 Islamic Revolution, and declared "we'r...