A retreat by NATO-trained Afghan forces in Kunduz this fall came after more than a decade of military operations against the Taliban. Many recognize the need to include the group in any political settlement.
The US airstrike on the Afghan hospital in which 22 people were killed has prompted Doctors Without Borders to call for an investigation into possible war crimes.
Monday's capture by the Taliban of the northern city was a blow to Kabul's efforts to pacify its foes.
Two gunmen in Afghan military uniforms opened fire on a vehicle carrying international troops in Helmand Province on Wednesday. It was the third reported 'green-on-blue' attack in Afghanistan this year.
A truck bomb in central Kabul Friday killed eight and injured hundreds. Insurgents attacks have cause 70 percent of civilian casualties this year.