WASHINGTON - Secretary of State Hillary Clinton heads to Afghanistan next week for a crucial conference that US officials hope will clarify the long-term goals of an expensive, unpopular and increasingly uncertain war.

Clinton will join dozens of other foreign ministers in Kabul on July 19-20 when Afghan President Hamid Karzai will detail plans to boost governance, security and economic opportunity in the face of relentless attacks by Taliban insurgents.

US officials want the meeting to highlight Afghanistan's drive to take on more responsibility for its future, one key to President Barack Obama's pledge to begin drawing down US forces in July 2011.