"[General Vo Nguyen] Giap ... saw the strategically ridiculous position in which the American military had been placed by President Johnson. Giap's military strategy was simple. He knew the US forces could tactically defeat his forces in head to head battles every day of the year due to the overwhelming fire power we could bring to bear, so he predicated his strategy on fighting battles, causing casualties among our troops and air crews, loosing the battle, accepting his losses large or small, and sending replacements into the South to repeat the process over and over again. As he said, we would run out of patience for that war long before he ran out of men." [emphasis added]
Looks like the Taliban are following the same course.