US Secretary of State Hillary Clinton is in Afghanistan to encourage President Hamid Karzai to continue efforts to reconcile with the Taliban. Mr Karzai has expressed frustration at the process after the assassinations of several key Afghan leaders. US officials say Mrs Clinton also wants to convince Afghans that Washington is committed to a long-term relationship with their country. The US is planning to withdraw troops and hand over security to the Afghans. "She wants to signal US support for a secure and stable Afghanistan," a US official told journalists travelling with Mrs Clinton. Her visit to Afghanistan was not...