Leon Panetta, who served as the chief of the CIA for 2 ½ years, has been sworn in as the 23rd secretary of the Department of Defense, succeeding Robert Gates.

A feature on the Navy Times shared that Panetta was sworn in on Friday at the Pentagon, by Defense Department General Counsel Jeh Johnson. In a message released on the day of his oath-taking, Panetta wrote about, among other things, striking a balance between defense needs and budget constraints: “While tough budget choices will need to be made, I do not believe in the false choice between fiscal discipline and a strong national defense… We will all work together to achieve both.”

He also wrote that the United States may proceed with transitioning out of Iraq, but it will not totally abandon the Iraqis: “We must cement a strategic relationship with the Iraqi government, one based not solely on our military footprint there but on a real and lasting partnership.”

In a video message for U.S. troops deployed worldwide, the new defense secretary declared: “Rest assured that … I will fight for you.”

In addition to serving as the chief of the CIA, Panetta served eight terms as a congressman, and was once budget chief at the White House. He is the oldest incoming defense secretary in history at 73 years old, and is the first Democrat at the helm of the Department of Defense since William J. Perry.

He is expected to begin visiting deployed U.S. troops this summer.