Pakistani troops killed three militants in an operation to secure the major supply route to US and NATO troops in Afghanistan, an official said Wednesday. Fazal Mahmood said the road through the famed Khyber Pass remained closed, but he hoped it would reopen soon. The US military has praised the campaign and said the temporary closure of the road was not a problem. Western forces in landlocked Afghanistan rely on the winding, mountainous road for delivery of up to 75 percent of their fuel, food and other goods, which arrive in Pakistan via the port city of Karachi. Militants have staged repeated attacks on supply convoys heading along the pass across Pakistan's western border to Afghanistan, where fighting is escalating seven years after a US-led invasion toppled a Taliban regime. On Tuesday, Pakistani security forces launched an operation using artillery and helicopter gunships in the Khyber area. "Our forces have killed at least three militants, and the operation is continuing," Mahmood told The Associated Press.