Defense Secretary Nominee James Mattis Pledges to Enforce Iran Nuclear Deal Criticized by Trump; Trump’s Pick for Defense Sec’y Made Millions in Defense Industry After His 2013 Retirement; Sent to the “Back of the Bus”? 3 Black Members of Congress Testify at End of Sessions’s Confirmation; James Mattis Calls for U.S. Military to Be More Lethal at Defense Secretary Confirmation Hearing.