Secretary of Defense James Mattis has announced he will resign at the end of February, in a letter publicly rebuking President Trump’s foreign policy. Mattis resigned one day after President Trump ordered the withdrawal of all 2,000 U.S. troops from Syria and on the same day that reports emerged that Trump has ordered the withdrawal of about 7,000 troops from Afghanistan. The New York Times reports Mattis is the first prominent Cabinet member to resign in protest over a national security issue in almost 40 years. Much of the Washington establishment expressed shock over Mattis’s resignation. We speak with Andrew Bacevich, a retired colonel and Vietnam War veteran. He’s the author of several books, including his latest, “Twilight of the American Century.” His other books include “America’s War for the Greater Middle East: A Military History” and “Washington Rules: America’s Path to Permanent War.” He is professor emeritus of international relations and history at Boston University.