Drone strikes are a key sticking point in shaping a security deal with Afghanistan that would allow a US presence after the planned troop withdrawal at the end of 2014.
Reversing a downward trend, civilian casualties have risen 23 percent, in part because of fighting between government forces and insurgents.
Evidence is mixed as to the readiness of Afghanistan's Army and National Police to assume the lead in planning and fighting – with the summer combat season likely to be the first big test.
The 13 soldiers killed were members of Afghanistan's Third Battalion, one of only a small number of Afghan Army units rated as fully self-sufficient by the US military.
The NATO-led coalition said a data entry error led to a claim last week that Taliban attacks had fallen 7 percent last year. In fact, there's little change. So what did we get for the surge?
Afghan President Hamid Karzai would like to make it very clear that he doesn't like the US, his principal protector and patron.