Rice arrived in Afghanistan from Pakistan, where she urged Islamabad to cooperate more closely with Kabul to defeat the Taliban. Violence in Afghanistan, especially in the south, is worse now than at any stage since the Taliban was driven from power in 2001.
"This is a very difficult time for both Afghanistan and Pakistan," Rice said. "There are attacks by these terrorists against both of these countries and I think they are united in wanting to defeat them."
Rice called Afghan President Hamid Karzai one of the most respected leaders in the world, and committed the United States to supporting Afghanistan in the long term.
Ahead of her visit, State Department spokesman Adam Ereli said Rice's visit was to intended "to continue our broad and effective engagement with Afghanistan to help strengthen democracy, the rule of law, stability, security, and prosperity in that country."