A Georgian official warned Russia on Friday that it will have to "collect the shattered fragments" of its planes if they intrude on Georgian airspace again.
Russia has confirmed that four of its planes circled over the Georgian breakaway province of South Ossetia late Wednesday for about 40 minutes, and that the mission was ordered to head off a possible "invasion" of the region by Georgian troops.
Georgia, which has accused Russia of aiming to annex the province, said the mission was an illegal invasion of Georgian airspace.
Both South Ossetia and another province, Abkhazia, have been outside the Georgian government's control since the end of separatist wars in the mid-1990s.
The planes flew over separatist-controlled South Ossetia, whose de facto border with Georgia is around 30 miles (50 kilometers) from Tbilisi, where U.S. Secretary of State Condoleezza Rice was on a visit.
Nikoloz Rurura, deputy chairman of Georgia's national security commission, said Friday that further overflights would not be tolerated.
"We are very seriously preparing our armed forces; they are able to unequivocally repel any such aggressive steps," Rurura told The Associated Press.
Hours earlier, officials in breakaway Abkhazia accused Georgian officials of plotting a blast that killed four there on Sunday.
Abkhazian presidential envoy Ruslan Kishmariya said Friday that an investigation proves "high-ranking employees of the Georgian Interior Ministry" were behind the blast.
The bomb exploded Sunday in a cafe in the town of Gali. The victims were a regional security chief, a U.N. translator, a local serviceman and a waitress.
Georgia dismissed the initial accusations as "absurd and groundless."
Russia does not formally recognize either region's separatist government, but it maintains close contacts with them and has granted passports to most of the regions' residents. Russia has peacekeeping forces in both regions; Georgia accuses the Russian forces of supporting the separatists.
Georgia has said it suspects Russia of using peacekeeping troops as a cover to bring artillery and other heavy weapons into Abkhazia, and has flown pilotless reconnaissance drones over the breakaway region.