Afghan officials say a roadside bomb destroyed a van in eastern Khost province, killing at least nine people and wounding seven others.
Authorities blamed insurgents for Wednesday's attack in Sabari district.
Meanwhile, U.S. officials, speaking on condition of anonymity, say President Barack Obama will most likely unveil key elements of his new strategy for the war Friday.
His recommendations are expected to include a call for increasing Afghan security forces, investing more in the country's development and possibly negotiating with some Islamic insurgents.
The Obama administration has said it believes a majority of insurgents can be convinced to lay down their weapons with the proper incentives.
In New York, the United Nations appointed former U.S. diplomat Peter Galbraith as U.N. deputy envoy to Afghanistan, responsible for political issues. Galbraith replaces Christopher Alexander of Canada, whose assignment ends at the end of March.
Militant violence in Afghanistan has increased to its highest levels since a U.S.-led coalition ousted the Taliban government in 2001.
Mr. Obama has already approved the deployment of an additional 17,000 troops to Afghanistan.
The U.S. president and other NATO leaders are scheduled to discuss the Afghan conflict at a summit in France and Germany next week.
NATO's top commander, U.S. General John Craddock, criticized parts of the current war strategy during testimony to the U.S. Congress Tuesday. He said NATO member countries have not provided enough combat troops and trainers for Afghanistan.
Some information for this report was provided by AP and Reuters.