Giving up American military leadership of the NATO alliance would be "problematic," the top U.S. general in Europe told senators Thursday. At an annual hearing before the Senate Armed Services Committee, Gen. Christopher Cavoli was asked about reports that the Trump administration is considering relinquishing the U.S. role as NATO's Supreme Allied Commander Europe, or SACEUR, a title that has been held by a U.S. general since its inception in the 1950s. As the chief of U.S. European Command,