Sy Hersh provides a useful look at evolving tactics on the ground in Iraq, but also advances a bit of a myth. Hersh compares current indications that the U.S. will move to a special op driven war of attrition against Iraqi guerillas to the Vietnam-era Phoenix program. Essentially, Phoenix used U.S. special op forces and CIA-trained South Vietnamese infiltrators to target and eliminate Viet Cong leaders.
Phoenix, Hersh tells us, was a failure and bad idea because "(s)ome of those assassinated had nothing to do with the war against America but were targeted because of private grievances."
But that just tells us that Phoenix wasn't exactly moral, not that it did not work. In fact, Phoenix's relative effectiveness is what has the Pentagon turning in that direction again.
Stanley Karnow also doubted the value of Phoenix until he talked to some of its targets. In his Vietnam: A History, Karnow quotes former Viet Cong leaders as calling Phoenix "very dangerous" and "extremely destructive" to their operations. Another credits Phoenix with wiping out "many of our bases" and forcing a wholesale retreat into Cambodia.
The brutal effectiveness of operations like Phoenix to quell a determined insurgency informs us why it is good idea to avoid policies—like occupation—which might coax a Phoenix forth.