> I know Ukraine will not and cannot do this, but writing off it's East and Crimea would enable NATO membership and EU ascension.
No, it wouldn't.
NATO deciding it was willing to piss off Russia (which is why, without those active conflicts, Ukraine and Georgia were denied MAPs in 2008) would allow NATO membership. There's no actual rule that would prevent Ukraine from joining during the invasion (and even if there was, any NATO rule can be changed, either in a general way or to add a sui generis exception, by the same group -- all NATO members agreeing together -- required to admit a new member under the existing rule, so the rule would not actually be an additional barrier.)
"But," you might object, "even if there is not a rule preventing it, Ukraine joining while the Russian invasion continues would be impractical because it would immediately trigger Article 5, as long as Russian forces were engaging Ukrainian forces anywhere in the country, or even occupying any part of the country."
That could be managed, though, by admitting Ukraine while adopting either a general (for later review) or temporary with explicit time limits or other terminating conditions exclusion of some parts of its territory from Article 5 (not all the territory of all NATO members is covered by Article 5 now.)
NATO could even allow Ukraine to join as a indirect declaration of war. If Russia attacks Finland (or any NATO country) today, Ukraine will probably be invited to join instantly - NATO would already be at war and expanding the scope help NATO (giving some place else to attack from) far more than the need to defend an additional country would hurt.
The entire purpose of joining NATO is to defend against russian imperialism (Something Sweden has a ton experience with, for hundreds of years) Always has been. There is not much point in joining if you exclude that bit.
Certainly the main purpose, but I think over the last 70+ years there are some other benefits to members.
For example, fostering trade of military goods and technologies between members (especially for the USA as a major exporter) and smoothing out their national budgeting since it's kind of like buying insurance.
What practical difference would joining NATO make in the short term though?
Ukraines problems are logistical and attrition and they have very strong NATO support. The red lines about prodding Russia will still exist and the supply shortages across the EU will as well.
Joining NATO makes sense in peace time and so diplomats can hang out at conferences and get formally connected to intelligence data. But how different is that to the data feeds Ukraine gets today?
> What practical difference would joining NATO make in the short term though?
Depends on the terms.
If, say, Article 5 excluded defined territories whose control was actively contested at the time or which were occupied by Russia with an explicit time limit, and applied fully to the rest of the country (including places Russia likes to lob missiles but cannot yet effectively contest for control of), that would pretty substantially change the Russian calculus of the war.
And especially if it also came with the kind of forward deployment (to the covered part of Ukraine) of NATO troops made to other eastern-flank countries, it would free up Ukrainian forces to deal with the contested and currently-occupied areas.
No, it wouldn't.
NATO deciding it was willing to piss off Russia (which is why, without those active conflicts, Ukraine and Georgia were denied MAPs in 2008) would allow NATO membership. There's no actual rule that would prevent Ukraine from joining during the invasion (and even if there was, any NATO rule can be changed, either in a general way or to add a sui generis exception, by the same group -- all NATO members agreeing together -- required to admit a new member under the existing rule, so the rule would not actually be an additional barrier.)
"But," you might object, "even if there is not a rule preventing it, Ukraine joining while the Russian invasion continues would be impractical because it would immediately trigger Article 5, as long as Russian forces were engaging Ukrainian forces anywhere in the country, or even occupying any part of the country."
That could be managed, though, by admitting Ukraine while adopting either a general (for later review) or temporary with explicit time limits or other terminating conditions exclusion of some parts of its territory from Article 5 (not all the territory of all NATO members is covered by Article 5 now.)