Defense Secretary Chuck Hagel announced Thursday that he had accepted the decision of his top deputy, Ash Carter, to step down from the Pentagon's No. 2 post.
Carter had been deputy defense secretary since October 2011, when he was promoted from his previous job as undersecretary of defense for acquisition and technology.
"He is a brilliant strategist and an excellent manager who helped enhance the department's buying power," Hagel said. "But Ash's most recent tour of the department will be especially remembered for his tremendous efforts to provide more agile and effective support for our warfighters and their families."
Carter, 59, will remain in his current job for two months, Hagel said.
The decision was announced during a meeting of senior Pentagon leaders, who gave Carter a standing ovation, Pentagon press secretary George Little said.
Little said the decision to leave "was Deputy Secretary Carter's and his alone." He stressed that Hagel and Carter have "a strong and effective working relationship and friendship."
Sen. Lindsey Graham, a South Carolina Republican and member of the Senate Armed Services Committee, praised Carter's work at the Pentagon.
"He has great mutual respect and admiration from senators on both sides of the aisle," Graham said. "During his time as deputy secretary, we have faced some of the most challenging times in the department's history. Ash Carter was always there, providing exceptional leadership at a time when it mattered."
Carter had also held a senior Pentagon post under President Bill Clinton. After graduating from Yale, he'd become a Rhodes Scholar and earned a Ph.D. in theoretical physics from Oxford University in England.
In between his government work for Clinton and President Barack Obama, Carter headed the international section of Harvard's John F. Kennedy School of Government and directed its preventative defense project.
The New Republic magazine two years ago named Carter to a list of the 25 "most powerful, least famous" people in Washington.
Carter, a Philadelphia native, is married to Stephanie Carter. They have two grown children.