Yet that deal has left some of the toughest questions to be hammered out later, among them U.S. access to military bases in Afghanistan, and the legal status of any soldiers that stay on after the NATO-led combat mission finishes at the end of 2014.
There are other major challenges facing efforts to shore up the civilian government in Kabul and ward off fears the country could fall into another civil war. Efforts to reach a political settlement with the Taliban are faltering, and there is little sign of progress on promised Afghan government efforts to tackle massive graft.
Crocker's departure may also be followed by that of the top U.S. and NATO commander in Afghanistan, General John Allen, according to Reuters news agency. The Obama administration is considering sending him to head U.S. forces in Europe this winter, the agency said this month, citing anonymous sources.
The turnover of the top civilian and military leaders of the U.S. effort in Afghanistan, before either man completed his term, would further complicate the transition to full Afghan control of security, at a time when cash for development spending is also being heavily cut.
Crocker, who previously served as U.S. Ambassador to Iraq from 2007 to 2009, warned near the start of his posting in Kabul that he thought the U.S. would have to spend a lot more time and billions more dollars in Afghanistan.
Crocker had retired from the government in April 2009, becoming dean of the Bush school of government and public service at Texas A&M University.
Intellpuke: You can read this article by Guardian correspondent Emma Graham-Harrison, reporting from Kabul, Afghanistan, in context here: www.guardian.co.uk/world/2012/may/22/ryan-crocker-step-down-ambassador-afghanistan