Russian irredentism

Russian irredentism is when Russia tries to take back lost lands (regions) it used to own. Russia has a long history of trying to take back parts of its former empires, and this is called irredentism. It is sometimes done to protect Russian culture or to gain resources. For example, in 2014, Russia annexed Crimea, a region of Ukraine that it used to own, because it believed the people there should be allowed to be part of Russia.