NATO has put its defense plans for the eastern flank into effect for the first time.
As Secretary General Jens Stoltenberg announced after a meeting of the North Atlantic Council, this took place after the "brutal act of war" at the request of the Commander-in-Chief for Europe (SACEUR), American General Tod Wolters.
"This is a wise and defensive move to protect and shield allies during this crisis," Stoltenberg said at Alliance headquarters.
Member states have given Wolters the authority to deploy the capabilities and troops “where they are needed”, including in the NATO Response Force.
This is the Alliance's rapid reaction force, which can grow from around 15,000 soldiers to three times as large.
On Friday, leaders will hold a virtual summit.
Political correspondent for the European Union, NATO and the Benelux countries based in Brussels.
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According to information from the FAZ, NATO activated a total of five - top secret - defense plans, from the Far North to the Baltic States and Poland, Romania and Bulgaria down to Turkey.
These are the so-called Graduated Response Plans, which have been in development since 2014.
These plans begin before a military confrontation and include graduated options to deter Russia from attacking NATO territory.
This includes pulling together the rapid reaction forces in the East.
Their advance warning time has recently been drastically reduced.
Stoltenberg: Russian invasion no surprise
The NATO Secretary General pointed out that the alliance had already significantly expanded its military presence in the past few weeks.
The allies kept more than a hundred warplanes on alert;
that is the number of ready-to-launch interceptors of all member states, not only in the east.
There are also 120 warships currently navigating Alliance territory.
The Russian invasion was not a surprise, Stoltenberg said, it happened exactly what NATO had been warning about for weeks.
In the early afternoon, Stoltenberg received the leaders of the European Union, Council President Charles Michel and Commission President Ursula von der Leyen, at Allianz headquarters.
The appointment was primarily intended to emphasize the unity of NATO and the EU.
Both will also take part in the video conference of the alliance's thirty heads of state and government, along with close partners Sweden and Finland - also with symbolic effect.
Stoltenberg cautiously hinted that the alliance is now also challenging the 1997 NATO-Russia Founding Act.
"We don't have all the answers today," he said, "but there will be a new reality, a new Europe."
There will be an important debate about this on Friday.
A statement from the North Atlantic Council said: "Russia's actions pose a serious threat to Euro-Atlantic security and will have geostrategic consequences."
As the FAZ reported, Chancellor Olaf Scholz, French President Emmanuel Macron and Polish President Andrzej Duda reached an internal agreement that they would consider the Basic Act lapsed in the event of an invasion.
The alliance could then station significantly more combat troops than before and also nuclear weapons on the territory of the former Warsaw Pact.