[drjme]

Russia’s Daily Online newspaper, Kommersant, also reported the presence of foreign mercenaries:

Authorities in the unrecognized republic of South Ossetia claim that dark-skinned mercenaries took part in the attack on Tskhinvali, reports RIA Novosti, citing representative of the South Ossetian president in Russia Dmitry Medoev. He said there were bodies of many Georgian soldiers on the streets on Tskhinvali. “There were blacks among the dead, who were probably either mercenaries or instructors in the Georgian armed forces,” Medoev said.
South Ossetian President Eduard Kokoity had said earlier that mercenaries were fighting with the Georgian forces. That information has not been confirmed in Tbilisi.

Last month, the United States, Georgia, Azerbaijan, Armenia, and Ukraine conducted Immediate Response 2008, a joint training exercise said to be in “spirit of the NATO Partnership for Peace program,” according to Blackanthem Military News. Immediate Response 2008 was held at the Vaziani Military Base in Georgia.
In another report, a woman interviewed by Russia Today in Tsknivali, South Ossetia, talked about the presence of Georgian troops with American insignias. “There are lots of bodies over there, a lot of people have been killed, mostly Ossetians, but also Georgians, they had American emblems on their forearms and they were in black uniforms,” she said.
Black uniforms are a trademark of Blackwater and DynCorp mercenaries (see Chris Hedges, America’s Holy Warriors). DynCorp’s presence in Eastern Europe is well documented, particularly in occupied Bosnia where it engaged in sex-trafficking and prostitution.
In a Friday press conference, Chairman of Russia’s State Duma Security Committee Vladimir Vasilyev said without U.S. aid, Tbilisi would have been unable to start military operation in South Ossetia. “The further the situation unfolds, the more the world will understand that Georgia would never be able to do all this without America,” said Vasilyev. “In essence, the Americans have prepared the force, which destroys everything in South Ossetia, attacks civilians and hospitals.”
It is entirely feasible the U.S. has “prepared the force” with mercenaries as well.

Georgian forces have been trained by 'American forces' since 2002 apparently. Russia would take decisive action against a proAmerican state starting hostilities near it's borders, one would think.
You wouldn't put it past companies like Blackwater to commit such acts, one only has to search youtube to see the appalling attitudes of the mercenaries in Iraq.

YouTube - Blackwater mercs murder innocent people.