The Russo-Georgian War was a war between Georgia, on one side, and Russia and the Russian-backed self-proclaimed republics of South Ossetia and Abkhazia, on the other. The war took place in August 2008 following a period of worsening relations between Russia and Georgia, both formerly constituent republics of the Soviet Union. The fighting took place in the strategically important South Caucasus region. It is regarded as the first European war of the 21st century.The Republic of Georgia declared its independence in early 1991 as the Soviet Union began to fall apart. Amid this backdrop, fighting between Georgia and separatists left parts of the former South Ossetian Autonomous Oblast under the de facto control of Russian-backed but internationally unrecognised separatists. Following the war, a joint peacekeeping force of Georgian, Russian, and Ossetian troops was stationed in the territory. A similar stalemate developed in the region of Abkhazia, where Abkhaz separatists had waged a war in 1992–1993. Following the election of Vladimir Putin in Russia in 2000 and a pro-Western change of power in Georgia in 2003, relations between Russia and Georgia began to deteriorate, reaching a full diplomatic crisis by April 2008. On 1 August 2008, the Russian-backed South Ossetian forces started shelling Georgian villages, with a sporadic response from Georgian peacekeepers in the area. Intensifying artillery attacks by the South Ossetians broke a 1992 ceasefire agreement. To put an end to these attacks, the Georgian army units were sent in to the South Ossetian conflict zone on 7 August. Georgian troops took control of most of Tskhinvali, a separatist stronghold, in hours.

Some Russian troops had illicitly crossed the Russo-Georgian state border through the Roki Tunnel and advanced into the South Ossetian conflict zone by 7 August before the large-scale Georgian military response. Russia accused Georgia of an "aggression against South Ossetia", and launched a full-scale land, air and sea invasion of Georgia, including its undisputed territory, on 8 August, referring to it as a "peace enforcement" operation. Russian and South Ossetian forces fought Georgian forces in and around South Ossetia for several days, until Georgian forces retreated. Russian and Abkhaz forces opened a second front by attacking the Kodori Gorge held by Georgia. Russian naval forces blockaded part of the Georgian Black Sea coastline. The Russian air force attacked targets both within and beyond the conflict zone. This was the first war in history in which cyber warfare coincided with military action. An information war was also waged during and after the conflict. Nicolas Sarkozy, the President of France, personally negotiated a ceasefire agreement on 12 August.

Russian forces temporarily occupied the Georgian cities of Zugdidi, Senaki, Poti and Gori, holding on to these areas beyond the ceasefire. The South Ossetians destroyed most ethnic Georgian villages in South Ossetia and were responsible for an ethnic cleansing of Georgians. Russia recognised the independence of Abkhazia and South Ossetia from Georgia on 26 August and the Georgian government severed diplomatic relations with Russia. Russia mostly completed its withdrawal of troops from undisputed parts of Georgia on 8 October. Russian international relations were largely unharmed. The war displaced 192,000 people. While many returned to their homes after the war, 20,272 people, mostly ethnic Georgians, remained displaced as of 2014. In 2021, the European Court of Human Rights ruled that Russia maintained "direct control" over the separatist regions and was responsible for grave human rights abuses taking place there.