US policymakers will watch Afghanistan's ability to maintain stability in Laghman Province as a litmus test for its forces' capabilities in the rest of the country.
US allies in Europe are mostly supportive of Obama's withdrawal plan, saying the time is right.
As Obama's promise of a troop drawdown nears, the US military says the surge of tens of thousands of NATO reinforcements that began last year has won some and lost some against the Taliban but needs more time to succeed.
A comprehensive congressional report finds that billions of dollars of US aid could be feeding corruption and establishing programs that will collapse when the US leaves.
President Hamid Karzai said Tuesday that the people of Afghanistan no longer desire to see international forces defend their country for them.
How journalist David Rohde and his wife coped when he was taken captive in Afghanistan
The deal, in which a prominent tribe has agreed to help stop Taliban attacks in volatile Helmand Province, is being compared with successful efforts in Iraq to use tribal influence against the insurgency there.