U.S. Secretary of Defense Chuck Hagel has resigned. Many observers were surprised by the sudden departure, even though President Barack Obama had indicated that he would be shaking up his foreign policy team in the wake of the disastrous midterm elections held last month. Officially Hagel is leaving because the global security environment has changed since he took the job less than two years ago: Picked to oversee a military transition from war to peace, Hagel was instead presiding over new forms of engagement — tasks that demanded a different set of tools.

Just as important, however, is how poorly Hagel fit into the Obama foreign policy team. Reportedly a friend of the president and an adviser on security issues before he joined the Cabinet, Hagel never really penetrated the inner circle of the White House. In an administration that has kept a tight grip on foreign policy, that exclusion, along with a growing sense of a need to change his foreign policy team, meant that Hagel was the obvious choice to go. It also means, however, that this change is unlikely to cure whatever ails the Obama foreign policy team.

Hagel was nominated to replace Leon Panetta at the beginning of Obama's second term. It was thought that as a Republican senator and a former soldier — he would become the first enlisted man to serve as secretary of defense — he would win support from a hostile GOP and prove to be somewhat insulated from partisan attacks as he cut the budget during the Pentagon's transition from a wartime footing to peace. Instead, Hagel was roundly attacked by his former colleagues, who viewed his criticism of the Iraq War, along with his friendship with the president, as apostasy. He got through the Armed Services Committee on a straight party vote and was ultimately confirmed with just four Republican votes.