From Time:

An episode last month illustrates the quandary American troops face. In early June, on the southern edge of Kandahar city, a small Army convoy drove into a nighttime ambush. Within seconds, a turret gunner in one of the vehicles was hit in the arm. Muzzle flashes pierced the dark, alerting fellow troops to where the shots were coming from. But, thinking that they had to clearly identify the triggerman before firing back, they waited before retaliating, even as rounds of hostile fire poured in. Only after an officer radioed back with the go-ahead did the Americans return heavy fire. By then, the militants had melted away.

The wounded soldier, Private First Class Trevor Longcore, of Shadow Troop, 1-71 Cavalry, caught a lucky break: he wasn’t hit by a bullet but by a piece of shrapnel that had apparently ricocheted off his vehicle’s armor. But a month into their deployment into Afghanistan, he and his compatriots are still frustrated by the constant heat-of-the-moment uncertainty about returning fire. For many troops, the strict rules of engagement — overlaid with tactical directives meant to limit civilian casualties — are a source of confusion and, they contend, are putting U.S. soldiers in greater danger. “We have all of these stupid rules that in the end wind up hurting more people. I mean, hesitation can mean death out here,” says one disgruntled soldier serving in the volatile south …

In Marjah, the desert town in central Helmand province where U.S. Marines are battling a resurgent Taliban, roving groups of militants on foot and motorbike take potshots at the Americans when they are not setting up ambushes and IEDs. Yet even if Marines see an attack taking shape around them, the current rules of engagement mandate that they cannot shoot unless they are first shot at. The insurgents know this, so they often “drop and go”: firing from a distance, then abandoning their weapons. Sometimes Marines never get a single shot off in defense, an exercise in restraint that is especially taxing for the American military’s hardiest warriors.

McChrystal’s advocates argue that McChrystal’s tactical directive was misunderstood and applied too restrictively at lower levels of command (the rules have been distorted as they pass down the chain of command).  But that dog won’t hunt.  His tactical directive remains available for viewing, and his words set the context for its application: “If you are in a situation where you are under fire from the enemy… if there is any chance of creating civilian casualties or if you don’t know whether you will create civilian casualties, if you can withdraw from that situation without firing, then you must do so.”  The reader can make up his own mind.

But without weighing in again on the restrictive nature of the ROE in Afghanistan, I will only observe one more time that while the rules for engagement of the enemy in Iraq were too restrictive, or so I argued, they were not the same as those in Afghanistan.  Period.  There is a difference, and you can judge for yourself how successful each campaign has been.  For a reminder of how insurgents were engaged in Iraq, see Recon by Fire (or what some commenters called the “Drake Shoot”).