(See the small area circled? That is the Suwalky Corridor. Russia has to go through either Poland or Lithuania to get to its territory of Kaliningrad on the Baltic Sea.
That is a major naval port for Russia and a military base. If those nations and Nato cut off Russian access, the only land route to Kaliningrad, it could start a war. And, that is exactly what those countries are going to implement against Russia within hours.)

Major crisis in the Baltic: NATO besieges Kaliningrad & takes battle positions at Suwalki Corridor
Interruption of Russia-Lithuania diplomatic relations
4/4/22 By Vassilis Kapoulas, WarNews24/7 (translated from Greek)

A major crisis erupts between Russia and NATO focusing on the Russian enclave of Kaliningrad in the Baltic.

Poland, Latvia, Lithuania and Estonia have decided to close their land borders with Russia and Belarus. The event completely isolates and cuts off the Russian enclave of Kaliningrad with Russia as the direct Russia-Kaliningrad air connection has been interrupted due to sanctions.

This move is a declared "cause of war" for Russia, something that has been repeated many times.

In fact, the commander of the Lithuanian army, Lieutenant General Valdemaras Rupshis, hastened to warn Moscow, saying that there was a joint defense plan to defend the "Suwalki Corridor" leading to Kaliningrad.

For the importance of Kaliningrad and the Suwalki Corridor ”read HERE (at source)

The Russian enclave of Kaliningrad is under siege
The Minister of Infrastructure of Ukraine Mustafa Nayyem noted that Poland, Latvia, Lithuania and Estonia will completely close the land corridors with Russia and Belarus in the next 48-72 hours, thus completely isolating Moscow.

"Last week, we formally called for the closure of motorways with Russia and Belarus. They responded to our appeal. We are waiting for the final result ", the Ukrainian minister added.

It should be noted that after the war in Ukraine, the European Union closed its airspace to Russian aircraft. Therefore, Russian transport is carried out only by road and rail.

Moscow warns - Cause of war for Kaliningrad
"Lithuania's decision to close the border with Belarus may end with the violent (!) Construction of a corridor to Kaliningrad

In this case, any transfer to and from Russia via Latvia, Lithuania and Estonia will be excluded.

Lithuania's decision to close its border with Belarus will call into question communications between mainland Russia and Kaliningrad. The Russian enclave "joins" with the Russian Federation through Lithuania and Belarus.

It is possible that the ban on Vilnius by the Russians crossing the border could lead to the violent creation of a corridor from the mainland to Kaliningrad, with all the ensuing consequences.

"Russia will once again be forced to take extreme measures to defend its national interests and territorial integrity,"he said.

Lithuania and Poland develop joint defense plan for Suwalki Corridor
Lithuania is ready to defend the Suwalki Corridor in the event of hostilities. "Poland and other NATO countries will help it."

This was stated by the commander of the Lithuanian army, Lieutenant General Valdemaras Rupshis.

Lithuania and Poland have developed a plan for the joint defense of the Suwalki Corridor - a strategically important 64 km section of the Lithuanian-Polish border between Belarus and the Kaliningrad region of Russia.

Vilnius fears that if this corridor is blocked by Belarussian or Russian troops, Lithuania will lose its land corridor and be completely cut off from the rest of Europe along with Latvia and Estonia.

For this reason, Lithuania and Poland have developed a detailed plan for the defense of the Suwalki Corridor, according to which a joint Polish-Lithuanian strike group has been set up to hold Russian troops until an allied force approaches.

These forces will come from Latvia, Estonia, as well as other NATO forces stationed in the Baltic states.

"A detailed plan has been drawn up to determine the units' position, maneuvers, support fire and air defense elements," said Lt. Gen. Rupshis.

If Russia builds a land corridor from Belarus to the Kaliningrad region along the Suwalki Corridor, then Moscow will be able to strike in any direction. The Baltic will be cut off by land from Europe.

Lithuania deports the Russian ambassador and also closes the consulate in Klaipeda. At the same time, the country's Foreign Ministry announced that the Lithuanian ambassador will leave Russia

For its part, Latvia has announced that it will reduce the level of diplomatic relations with the Russian Federation due to crimes committed by the Russian armed forces in Ukraine,

Lithuania's deportation of Russian ambassador to Baltic state after Ukraine accused Russian forces of killing civilians in the town of Buka, the Lithuanian Foreign Ministry said today.

The Russian ambassador to Lithuania "should leave the country, " the Lithuanian Foreign Ministry said in a statement.

"Lithuania stands in full solidarity with Ukraine and the Ukrainian people, who are victims of Russia's unprecedented aggression," Foreign Minister Gabriel Lantzbergis said in a statement.

"War crimes and crimes against humanity committed by the Russian armed forces in Ukraine will not be forgotten," he added.

Lithuania also said it would close the Russian consulate in the port city of Klaipeda and said its envoy to Moscow "would return in the near future".

Neighboring Latvia, meanwhile, has said it will take steps on diplomatic relations with Russia without elaborating.

"Given the atrocities committed by the Russian armed forces in Ukraine, Latvia will tighten diplomatic relations with the Russian Federation," Foreign Minister Edgar Rinkevics wrote in a Twitter post. "Special decisions will be announced as soon as the internal procedures are completed," he added.

Source:
https://warnews247.gr/meizona-krisi-stin-valtiki-to-nato-ethese-ypo-poliorkia-to-kaliningkrant-elave-theseis-machis-ston-diadromo-suwalki-aitia-polemou-leei-i-moscha/