Russian irredentism refers to territorial claims made by the Russian Federation to territories that were historically part of the Russian Empire and the Soviet Union, which Russian nationalists refer to as the "Russian world". It seeks to politically incorporate ethnic Russians and Russian speakers living in neighbouring territories outside Russia's modern-day borders. This ideology has been significantly defined by the regime of Vladimir Putin, who has governed the country since 1999.

The "Russian world" is a concept and a political doctrine usually defined as the sphere of military, political and cultural influence of Russia. This concept is sometimes also phrased as Pax Russica, in parallel to the Pax Romana, and as a counterweight to the Pax Britannica of the nineteenth century and the Pax Americana after WWII.