In a conversation on May 15 in Copenhagen with Anders Fogh Rasmussen, his predecessor as NATO Secretary General and now chairman of the Alliance of Democracies Foundation, Jens Stoltenberg indicated that bilateral promises of security guarantees by individual NATO members with a non-NATO country could lead to the invoking of the infamous Article V of the NATO Treaty, which calls for mutual military defense if a member comes under attack.
Stoltenberg claimed that the only way to stop further “Russian aggression” is “to ensure that Ukraine has the military strength to deter and defend against further aggression from Russia, but also to find some kind of framework to prevent Russia, or President Putin, from continuing to chip away at European security.”
“Exactly what kind of framework, I cannot tell you now, but what I can say is that if NATO Allies and especially of course, the big ones, start to issue security guarantees bilaterally to Ukraine, we are very close to Article V,” he went on. “So there is no way to find an easy solution to these issues. The most important thing is to be very strong in our support for Ukraine so Ukraine will prevail as a sovereign, strong, independent nation in Europe.” (https://www.nato.int/cps/en/natohq/opinions_214381.htm)
Article V is the provision of the NATO Treaty that declares that an attack on one member of the alliance is an attack on all members, thus opening the door to expanding the conflict to the level of a general war. Under Stoltenberg’s scenario, Russia’s special military operation in Ukraine could be construed to trigger Article V.