In his new book, Age of Iron, leading authority on Republican foreign policy, Colin Dueck, describes the shifting coalitions over the past century among foreign policy factions within the Republican Party and shows how President Trump upended them starting in 2015-16. Professor Dueck offers a balanced summary and assessment of Trump’s foreign policy approach, analyzing its strengths and weaknesses. He also describes the current interaction of conservative public opinion and presidential foreign policy leadership in the broader context of political populism. Finally, he makes the case for a forward-leaning realism, based upon the understanding that the U.S. is entering a protracted period of geopolitical competition with other major powers. The result is a book that captures the past, present, and, possibly, future of foreign policy in the United States.