Šešupė in the context of "Marijampolė"

The German–Soviet Boundary and Friendship Treaty was a second supplementary protocol of the Molotov–Ribbentrop Pact of 23 August 1939. It was a secret clause as amended on 28 September 1939 by Nazi Germany and the Soviet Union after their joint invasion and occupation of sovereign Poland. It was signed by Joachim von Ribbentrop and Vyacheslav Molotov, the foreign ministers of Germany and the Soviet Union respectively, in the presence of Joseph Stalin. Only a small portion of the protocol, which superseded the first treaty, was publicly announced, while the spheres of influence of Nazi Germany and the Soviet Union remained secret. The third secret protocol of the Pact was signed on 10 January 1941 by Friedrich Werner von Schulenburg and Molotov, in which Germany renounced its claims on a part of Lithuania, west of the Šešupė river. Only a few months after this, Germany started its invasion of the Soviet Union.

The Lithuania–Russia border is an international border between the Republic of Lithuania (EU member) and Kaliningrad Oblast, an exclave of the Russian Federation (CIS member). It is an external border of the European Union. The 274.9 km (170.8 mi) long border passes (from west to south-east clockwise) through the Curonian Spit and Curonian Lagoon, and then follows along the Neman River, Šešupė, Širvinta, Liepona, and Lake Vištytis. The sea border is another 22.2 km (13.8 mi). There is a tripoint between Lithuania, Russia, and Poland with a stone monument at 54°21′48″N 22°47′31″E / 54.36333°N 22.79194°E / 54.36333; 22.79194.

Most of the border follows rivers or lakes. On land, border stations are equipped with engineering and technical facilities (wired fences and the exclusion zone). Most other land areas have no fence, but some places near roads or villages have fences (e.g. at 54°27′11″N 22°42′08″E / 54.45306°N 22.70222°E / 54.45306; 22.70222 with Street View coverage). Russians need a Schengen visa to cross the border into Lithuania, and Lithuanians need a Russian visa to go to Russia.