Debating nine of her rivals for the Democratic Party’s nomination for president on Tuesday, Sen. Elizabeth Warren (D-Mass.) made her case again for a U.S. policy against first use of nuclear weapons. “The United States is not going to use nuclear weapons preemptively, and we need to say so to the entire world. It reduces the likelihood that someone miscalculates, someone misunderstands,” Warren said during the CNN debate in Detroit. “Our first responsibility is to keep ourselves safe. And what's…
