President Barack Obama's national security adviser, Gen. James Jones, will step down in two weeks, the White House announced Friday.

Obama said Jones, who spent 40 years as a Marine, never planned to stay on the job more than two years. His deputy, Tom Donilon, will take his place.

Jones, 66, helped shaped U.S. foreign policy since Obama took office, working to end the war in Iraq, expand the war in Afghanistan, and improve relations with other countries.

"Through these challenges, Jim has always been a steady voice in Situation Room sessions, daily briefings, and with meetings with foreign leaders, also representing our country abroad with allies and partners in every region of the world," Obama said in a Rose Garden ceremony Friday.

Obama also described Jones as a "dedicated public servant and a friend."

Jones' resignation came just one week after Chief of Staff Rahm Emanuel announced he'd be stepping down to run for Chicago mayor.