"For more than a year, General Allen has served with distinction as the Commander of US Forces and NATO International Security Assistances Forces in Afghanistan, seeing us through a critical period in our military efforts and in Afghanistan's transition," Obama said.
Two top United States officials have called off visits to Islamabad without assigning any reasons, reflecting the current tensions between the two countries as they struggle to reset their troubled ties a year after the killing of Al Qaeda's Osama bin Laden.
Pakistan Army chief Gen Ashfaq Parvez Kayani on Thursday called for transparent ties with US based on mutual trust as he met American commander in Afghanistan, days after the two sides struck a deal ending a seven-month blockade of NATO supply routes.
A top American commander based in Afghanistan has submitted plans to the Pentagon that would keep 6,000 to 20,000 US troops in the war-torn country after 2014.
The United States may keep a combat force of around 10,000 in Afghanistan, including a small counter-terrorism force after 2014 as a contingency against re-emergence of the Al Qaeda.