Throughout all of Afghanistan, there is that one part that troops know they don't want to be sent to. Over 40 American servicemen and countless Afghan troops have been killed in this one area alone. The Korengal Valley is on the Eastern part of Afghanistan and borders Northern Pakistan. This area is a very strategic location for Taliban fighters, as the US has limited involvement in Pakistan (mainly just drone strikes, after the Bin-Laden raid there is no question SOCOM has involvement as well) and this is where many of them cross the border.
The terrain within the Korengal Valley is very mountainous and hilly. This makes it difficult for ISAFs to secure the area. What they do, is set up numerous firebases and patrol the surrounding areas. Some of the territories throughout the valley are known Taliban strongholds, and it is almost expected that there will be fighting there when patrolled.
It is hard to fight there, especially when relations with the local tribal leaders are extremely important. Though the ISAF does its best to avoid them, incidents do happen. An accidental bombing of a village, a stray mortar landing in a school yard. This is in addition to the punishment that the Taliban initiates for collaboration. There is no question about it, life in the Korengal Valley is tough for everyone.