The Senate on Tuesday unanimously approved CIA Director Leon Panetta as the new secretary of defense, succeeding Robert Gates when he steps down at the end of June. A former Cabinet official under Bill Clinton and a former congressman, Panetta pledged to be a “tireless advocate for our troops and their families.” President Obama has nominated Gen. David Petraeus, who is heading up the Afghan mission, to lead the CIA, the position Panetta has held since 2009.