KABUL, Afghanistan, May 22 (AP/UNB) - The U.S. Embassy in Kabul says Ambassador Ryan Crocker will be leaving his post this summer.

Crocker, 62, came out of retirement last July to take over as the top U.S. diplomat in Afghanistan.

Crocker became 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.

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

Acting embassy spokesman Mark Thornburg said Tuesday that Crocker confirmed, with regret, that he will be leaving Kabul this summer.

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