Sure they can. If they declare war and officially enter the conflict. That wouldn't be a NATO action though, it's a defensive pact.
And it won't happen. Although... the last few days have shown extraordinary events that I never expected. The EU approving 500 Million for weapon purchases for Ukraine, countries supplying fighters after two days delay, officiaks saying that their are fine with their citizens volunteering to fight for another state army (illegal pretty much everywhere), plans to supply troop movement intelligence... That's all just a very small step from active participation.
This is the most significant shift in European politics since the fall of the Soviet union.
"A war of aggression, sometimes also war of conquest, is a military conflict waged without the justification of self-defense, usually for territorial gain and subjugation."
I'm reading a lot about the 37' Spanish war atm, and there is some common points between the reactions of NATO and the then Alliance. Hopefully we won't have a Stalin in our rank betraying everybody.
When and in what circumstances? There are military accidents, or what can plausibly be called accidents. Intentionally shooting down a plane, especially during a war, is another matter.
That's basically what was done the whole Cold War. USA goes to Vietnam --> USSR supports the other fraction with weapons etc. USSR goes to Afghanistan --> USA supports the Afghans etc.
Having Cold War situations again isn't desirable of course but it's kind of battle tested to not lead to further, direct, escalations.
You're right in theory. In reality, though, allowing citizens to call him President Putain is a casus belli, as far as Russia is concerned, so I'm not sure what actual difference it makes.
For the record, Russia also said sanctions would be considered an act of war. ¯\_(ツ)_/¯
Russia says a lot, I wouldn't believe all of it to be either honest or true.
That aside Russia coming up with it's own reasons for engaging in war with a country is different than Russia having internationally recognized reasons for engaging in war with a country.
> That aside Russia coming up with it's own reasons for engaging in war with a country is different than Russia having internationally recognized reasons for engaging in war with a country.
Can you explain? Is there another internationality, except UN, which has authority to allow wars?
> Is there another internationality, except UN, which has authority to allow wars?
Kind of. International law is made up of both treaties and customary international law, which is (to oversimplify) basically a distillation of state practice. Think of it as almost analogous to statues vs. common law.
For example, while the U.S. is not a party to the U.N. Convention on the Law of the Sea, it recognizes most of its tenets as customary international law. (This is also why it regularly conducts freedom of navigation passages in the South China Sea, to prevent China's ownership claim from becoming customary international law.)
If a large number of nations (say, NATO?) agreed that another lawful basis for the use of force (LBUF) existed, beyond the right of self-defense or an UNSCR, that could become customary international law. The hot topic in this area right now is humanitarian intervention, which NATO cited in its Kosovo intervention and which the UK recognizes as a CIL LBUF. This gets meta real fast, since even though a large number of nations reached consensus on using it as justification for Kosovo, they haven't reached a consensus that there is a consensus on using it. Only the UK explicitly recognizes it as CIL, last I checked.
So what you see instead is this kind of academic song and dance where, e.g., the U.S. de facto is using humanitarian intervention to justify intervention in Syria but de jure relies on a mildly stretched interpretation of self-defense instead.
And it won't happen. Although... the last few days have shown extraordinary events that I never expected. The EU approving 500 Million for weapon purchases for Ukraine, countries supplying fighters after two days delay, officiaks saying that their are fine with their citizens volunteering to fight for another state army (illegal pretty much everywhere), plans to supply troop movement intelligence... That's all just a very small step from active participation.
This is the most significant shift in European politics since the fall of the Soviet union.