A perennial problem for the US during the Vietnam War was to turn the South Vietnamese Army into a real army so that US troops could leave. Why did it fail with all that $$$ and hardware handed to Saigon?
The North Vietnamese and the Vietcong would salivate at gaining access to all that supply of resources.
Yet with all the help handed to the South, it was futile. The South Vietnamese soldiers didn't really want to stand up and fight because they knew they didn't have the people supporting them. Their own proverbial brothers-in-law were mostly on the "other side". In this case, at least not on their side.
Read this article from Stars and Stripes here and you see the similarities between the Iraqi and the Vietnamese wars. Not two wars are the same, but one thing stood out.
The Iraqi security forces ain't worth didley without US troops and the latter are more feared than loved for they have clearly produced a lot of "collateral damage". Would you welcome US troops if you were an innocent Iraqi in their ways?