In international relations, revanchism is the desire of a group to enlarge its borders to include territory it believes was unfairly taken from it. Most commonly, it focuses on territory lost due to war, but it could include areas broken out of traditional lands by self-determinative plebiscites and similar processes. It is closely related to irredentism, where other areas were not necessarily taken away, but are believed to be a logical part of a nation.
An arguable case is the Aztlan movement, which wants to restore, to Mexico, land it believes was taken by the United States. Some believe this is seriously intended, others see it as an issue being raised by anti-immigration groups, while others see it as a political wedge issue used for rhetoric. 
Some Japanese desire return of the Kurile Islands, which has also been supported by China as a brake on Russia.  The Kuriles were granted to the Russians as a result of the Yalta Conference, given the United States thought they were of little value, but would be an inducement of Soviet entry into World War II in the Pacific.
There are a number of claims involving inappropriately drawn boundaries following decolonialization.
Nazi foreign policy used many revanchist arguments. One important claim was the inclusion of German-majority Sudetenland in Czechoslovakia. Another came from traditional lands being made discontiguous, as with the Polish Corridor between the port of Danzig (now Gdansk) and Germany.
- Georgians Fear Russia’s Revanchism as Noghaideli Forecasts ‘Uprising’, Jamestown Foundation, 9 April 2010
- The Quest for Aztlan
- McCain to attend convention of 'reconquista' group, WorldNetDaily, 5 May 2008
- Chicano Nationalism, Revanchism and the Aztlan Myth, Federation for American Immigration Reform
- MM Kunju, PA George, ed., Japanese Studies Changing Global Profile, Northern Book Centre, pp. 148-151