Presidents and not their aides are responsible for setting the course of U.S. foreign policy, and in the case of President Barack Obama, that has been true arguably to a fault.
It was Obama who insisted, over the objections of some advisers, that Israel's settlement construction should be the focus of his first-term Middle East peace initiative. It was he who decided that the surge of troops in Afghanistan should be accompanied by a fixed withdrawal date. And it was he who rejected the advice of most of his senior national security aides last year that the United States should arm Syria's rebels.
More broadly, Obama appears to be the animating force behind what increasingly looks like a broad U.S. retreat from its longtime role as the world's "indispensable nation." In addition to shunning intervention in Syria, where what is now a devastating civil war might have been prevented, the president chose to withdraw all U.S. forces in Iraq after 2011, leaving his administration with few means to prevent the unraveling of that country's postwar democratic order. He has spoken frequently of "nation-building here at home," and of allowing allies or the United Nations to take the lead on foreign crises.