Georgia has protested after Russia temporarily expanded its Olympic security zone into the breakaway Georgian territory of Abkhazia.
It said Russia had created the new zone, 11km (seven miles) inside Abkhazia, for the duration of the Winter Olympic Games in nearby Sochi.
The Georgian government expressed "deep concern" over the "illegal expansion".
Russia is one of the few countries to recognise Abkhazia as a sovereign state since it broke away from Georgia.
It is conducting the biggest security operation in the history of the Olympics for Sochi, which is less than 40km along the Black Sea coast from Abkhazia.
The main threat of terrorist attack is seen as coming from Islamist militants based in the Caucasus Mountains.
Abkhaz security forces will patrol the new border zone and local residents will have to carry ID cards at all time.
Abkhazia and fellow breakaway Georgian region South Ossetia receive financial support from Moscow and are under Russia's military protection.
Russia and Georgia have had no diplomatic relations since their brief war in 2008 over South Ossetia, although economic ties have partially been restored since the change of government in Georgia in 2012.
While Russian officials did not confirm the border move, the Georgian foreign ministry said it would last until 21 March, when the Olympic Games and Paralympic Games are over.