Russia has now taken the matter to the UNSC, posing as the "moderate" party of reason in the affair (RFE/RL):
Update: As the four servicemen accused of espionage appear in a Tbilisi court, warnings have started to come from various Russian sources:
Russia's UN ambassador, Vitaly Churkin, said after an emergency session of the council that he had circulated a draft statement expressing deep concern over Georgia's actions.
"We are concerned by the tendency of the Georgian authorities to fuel tensions, so we are calling on the Security Council and the international community to exert its influence on the Georgian side, so that instead of provocative actions and fueling tensions they engage in constructive dialogue," he said.
NATO Secretary-General Jaap de Hoop Scheffer has called on Russian and Georgia to "de-escalate tensions" over the espionage affair. The United States and the EU have also urged calm.
...Fyodor Lukyanov, editor in chief of the journal "Russia in Global Affairs," told RFE/RL that Russia could well resort to tougher measures should negotiations fail.
"So far [Russia's reaction] is still rather moderate. No irreversible steps have been taken. But the way things are developing is very unpleasant, and if no outside influence is exerted, for instance, on Georgia to make it reduce the tension, Russia's reaction could stop being moderate," Lukyanov said.