Improvised explosive devices, or IEDs, are the biggest threat facing troops engaged in an assault on a Taliban stronghold in southern Afghanistan, military commanders have said.
US Marines are leading 15,000 US, NATO and Afghan troops in an operation to clear the Marjah and Nad Ali districts in Helmand province of Taliban militants who have controlled the region, along with drug traffickers, for years.
The aim of Operation Mushtarak ("together" in Dari), is to re-establish Afghan government control so security and civil services such as police stations, schools and clinics can be set up.
Commanders say areas have been heavily mined with IEDs by Taliban fighters as they have fled or melted into the local population.
The homemade bombs have been found planted in roads and fields, hanging from trees and even plastered into walls, Afghan Army Colonel Shirin Shah told AFP.
IEDs -- mostly made from fertiliser, fuel and metal --are exacting a high price from the world's most sophisticated armies and have become the pivot on which the eight-year war is turning.
The Taliban weapon of choice is killing foreign troops in record numbers -- US military intelligence says up to 90 per cent of foreign troop casualties are now caused by IEDs.