KABUL, Afghanistan — Veteran U.S. diplomat Ryan Crocker will be leaving his post as ambassador to Afghanistan this summer, an embassy spokesman said Tuesday.

Crocker, 62, came out of retirement last July to take over the post after a request from President Barack Obama. Crocker was widely known for his role as U.S. ambassador to Iraq from 2007 to 2009.

It is unclear why he is leaving the post a year ahead of schedule or who will replace him. The most likely candidate would be James Cunningham, one of four other ambassadors serving under Crocker in Kabul.

There have been persistent rumors that Crocker wanted to leave for personal reasons. The U.S. Embassy last denied such a rumor two weeks ago.

“Ambassador Crocker has confirmed, with regret, that he will be leaving Kabul this summer,” acting embassy spokesman Mark Thornburg said.

Crocker also served as U.S. ambassador to Lebanon, Pakistan, Kuwait and Syria.

He arrived here at the same time as Marine Gen. John Allen, the top U.S. and coalition commander in Afghanistan.

Crocker retired after his stint as ambassador to Iraq and became dean of Texas A&M University’s George Bush School of Government and Public Service.

He is currently in the United States, where he attended a NATO summit in Chicago.