Final answer:
The Nemunas River flows through Lithuania after originating in Belarus, forming part of the Lithuania-Russia border, and empties into the Curonian Lagoon.
Step-by-step explanation:
The Nemunas River mainly flows through Lithuania, after originating from Belarus. It does indeed form part of the border between Lithuania and the Russian enclave of Kaliningrad before emptying into the Curonian Lagoon, which then leads to the Baltic Sea. It is not to be confused with the eastern rivers like the Irtysh or Lena which flow northward into Siberia and the Arctic Ocean. The Baltic states, including Lithuania, gained independence from the Soviet Union in 1991 and have been transitioning towards Euro-Atlantic integration with memberships in organizations like the European Union (EU) and the North Atlantic Treaty Organization (NATO) since 2004.