A Pentagon report on Afghanistan said progress in the nine-year-old war was fragile, but holding.
The latest bi-annual report to congress comes as violence is on the rise and more Afghans say they fear for their safety.
Barack Obama's administration chiefs said the findings represented a slight improvement from previous months.
The report is an early look into the kind of cautious assessment expected to reach the president's desk next month. The December review is supposed to determine whether Mr Obama's war strategy, which includes a build-up of some 30,000 troops, is succeeding in breaking the momentum of the Taliban uprising.
"The deliberate application of our strategy is beginning to have cumulative effects, and security is slowly beginning to expand," says the report, which looks at operations from April to September 30.
Still, the report adds, the number of Afghans rating their security situation as "bad" is the highest its been since 2008, with "kinetic events" increasing by more than half during the summer. The report attributes the uptick in violence to increased fighting between US-led forces and the Taliban.
A senior defence official said the Pentagon viewed the war as an "extraordinarily dynamic situation". They said officials believed much had already changed since the report's end date, including military progress in the key city of Kandahar.
At the Nato summit in Lisbon, Portugal, last weekend, European countries eagerly embraced an agreement to begin handing over security responsibility to the Afghans in early 2011 with full transition targeted by the end of 2014.
General David Petraeus, the top US and Nato war commander in Afghanistan, said in Paris that the coalition's goal in Afghanistan was not to turn the country into a democratic republic like Switzerland, but rather to raise its security and governance to a level when Afghans could take the lead.