New Secretary of Defense Chuck Hagel is greeted by USMC Lt. General Thomas Waldheuser, who will serve as Hagel's Senior Private Military Assistant, as he arrives for his first day at the Department of Defense, on Feb. 27, 2013 in Arlington.

Hagel was sworn in as the defense secretary at a small, closed-door ceremony on Wednesday after an arduous confirmation battle in the Senate. He becomes the first Vietnam veteran and the first former enlisted soldier to take up the post.

"I am honored that President Obama and the Senate have entrusted me to serve our nation once again," Hagel said in a written statement. "I can think of no greater privilege than leading the brave, dedicated men and women of the Department of Defense as they perform vital missions around the globe. I will work closely with Congress to ensure that we maintain the strongest military in the world and continue to protect this great nation."