President Obama has announced the resignation of Secretary of Defense Chuck Hagel.
Observers believe the president and Hagel didn't see eye-to-eye on the strategy to combat ISIS. Hagel became defense Secretary about two years ago and was brought in to wind-down U.S. deployment overseas. But the escalation of conflict in Iraq and Syria had seen ramped up U.S. military operations in that region.
"When it’s mattered most behind...