Why is the U.S. military protecting Blackwater mercenaries

Buried in the U.S. Embassy whitewashreport on the September 16 incident in which Blackwater mercenaries fired on Iraqi civilians is this little tidbit:

According to the report, a third Blackwater team, identified as TST 23, was dispatched from the Green Zone to assist after the car bomb detonated. Upon arriving at Nisoor Square, in Baghdad's affluent Mansour neighborhood, the report said, TST 23 was "engaged with small arms fire" from "multiple nearby locations."

The report said TST 23 returned fire and tried to drive out of the ambush site. However, one of the company's tactical armored vehicles, a BearCat, became disabled during the shooting. In the middle of the firefight, according to the report, the other tactical support team, TST 22, was ordered back out of the Green Zone to assist TST 23 in Nisoor Square, identified in the document as Gray 87.

Before TST 22 could arrive, according to the report, TST 23 had towed the BearCat and returned to the Green Zone. TST 22 found itself alone in the congested traffic circle and confronted by an Iraqi quick-reaction force. "Over the next several minutes, additional Iraqi Army and Iraqi Police units arrived and began to encircle TST 22 with vehicles," according to the report. "The Iraqis had large caliber machine guns pointed at TST 22."

"The U.S. Army QRF" -- quick-reaction force -- "arrived on scene at 12:39 hours and mediated the situation," the report said. "They escorted TST 22 out of the area and successfully back to the [Green Zone] without further incident."

Is this now the mission of the United States Army -- to protect Bush's Praetorian Guard-in-training?