The Donald Trump administration seems to value change for its own sake. The new President appears intent on rethinking all foreign-policy rules and norms, from diplomatic protocols to staffing to relationships with traditional allies. The next four-to-eight years may prove to be a watershed for U.S. grand strategy, a challenge to fundamental assumptions that forces security experts to re-examine their most deeply held beliefs. Or, perhaps little will change. At the very least, the Trump administration will test the notion that U.S. foreign affairs are marked far more by consistency than by change.