Russia’s neighbors fear NATO’s defense plans are not fit for purpose and they could be quickly overrun

Lithuanian President Gitanas Nauseda has said he plans to bring up a stand-off with Russia at this week’s NATO summit.

The security environment on Europe's eastern flank has changed as a result of Russia's invasion of Ukraine. Ahead of this week's NATO summit in Madrid, the three Baltic countries of Estonia, Latvia and Lithuania have sent a unified message.

One of the most important decisions NATO leaders will have to make is the defense of the Baltic region.

The military alliance is going to reflect on how they can respond to Europe.

We need to move to deterrence by denial. We need a credible military construct on the Eastern flank that will deter Putin.

The Baltic countries are worried that they may be Putin's next military target.

All member states of both NATO and the European Union have repeatedly called on NATO to provide a substantial increase in the number of foreign troops stationed in the region.

The Baltic countries want an update to the alliance's "tripwire" approach.

According to The Financial Times, the Prime Minister of Estonia warned that the former Soviet state would be wiped off the map if a Russian attack were to take place.

Kallas has said Estonia faces an existential threat under NATO’s current plans to protect the country from a Russian attack.

Kallas told reporters last week that NATO's tripwire approach, which involves a relatively small number of troops, would likely cause Estonia to be overrun before NATO could liberate them.

The tripwire approach is obsolete because of atrocities committed by Russian forces in two western suburbs of Kyiv.

We want you to stay away because you will lose. They said to not think of coming. By denying, we need to move to deterrence. The Eastern flank needs a military construct that will deter Putin. More Allied presence should be included.

A NATO spokesman was not available to speak.

Since the beginning of the year, the U.K. has doubled its forces in the country, which is a NATO framework nation. France and other countries have increased their presence in the country.

The geographic location of the Baltic states makes them vulnerable even though they have joined NATO and the EU. They all have a border with Russia.

There is a western border with the Russian exclave Kaliningrad that is shared byLithuania and Russia.

A new front of tensions between Russia and NATO has been created by the Kremlin's outpost on the Baltic Sea.

The transit of EU-sanctioned goods from Russia to Kaliningrad has been banned byLithuania. The Kremlin warned that the citizens of the Baltic state would feel the pain.

The president ofLithuania said last week that he didn't expect Putin to attack if Russia disconnected it from the grid.

The stand-off with Russia may help to calm those who say that we must help Russia to save face while it threatens us.

His comments appeared to be a thinly veiled reference to comments made by France's President that it would be foolish for the West to humiliate Putin.

Europe needs NATO leaders to agree on a new baseline for the alliance's posture in the region. Moving from forward presence to forward defense is known as deterrence by denial.

Russia's military superiority in the region, the Kremlin's military integration with Belarus and the "Suwalki corridor" are some of the reasons cited by the foreign ministry of Lithuania.

All of the Baltic nations have pledged to increase defense spending to 2.5% of GDP, which would surpass the 2% benchmark set by NATO.

The Laima Clock landmark in central Riga.

NATO's deterrence and defense posture would be one of the main objectives at the Madrid summit, according to the foreign ministry of the country.

The strategic security environment in the Euro-Atlantic area changed irreversibly after the start of the Russian aggression against Ukraine. A fundamental shift in NATO's long-term deterrence and defence posture is needed.

The commitment to defend every inch of Allied territory is ironclad. The posture will be strengthened. There is an Allied presence in the Member states bordering Russia.

Collective defense is a pillar of the NATO alliance and means that if one member is attacked, it is considered an attack on the entire group with all members committed to protecting each other.

Holly Ellyatt worked for CNBC.