Deep connections dating back centuries; many Eastern European countries were part of the Russian Empire or USSR, with significant Russian-speaking populations.
Eastern Europe provides strategic depth against Western influence and NATO expansion, which Russia views as a security threat.
Access to oil, gas, and minerals in some Eastern European countries benefits Russia's energy security and economy.
Russian military bases in the region allow power projection and political influence.
Eastern European countries are key trading partners, providing markets for Russian goods.
Strong ties give Russia a say in regional affairs and international organizations.
These factors make Eastern Europe a strategic priority in Russian foreign policy.