Did you bother to read the NATO link you posted?
It clearly states that the threat of nukes is extremely low (not higher than 5%).. that puts the threat very low on the matrix... and really isnt any different than considering the Russian nuclear threat in any other situation or scenario..
I'll also ask if you actually read the brookings or hoover articles previously posted.. they make very clear assertions as to the reason the US should be involved.. that are very similar to what
@Red Leg and others have already stated here, but you seem to not be able to comprehend..
"in late spring some US strategists and officials advocating permanently weakening Russia as a strategic goal"
the brookings article speaks to the detriment to the West of a Sino-Russian bloc in geopolitical order if the Russians arent thwarted.. and supporting the ukranians is a strategy to thwart this..
it speaks to Russias relatively small GDP, but their scientific capabilities and what its minority partnership value would be to the Chinese (a clear threat to both our economy and our security)... The US has a strategic interest in not seeing this happen..
It speaks to Russias permanent position on the UN Security Council and the reasoning that the UN really cant position itself to counter balance a Sino-Russian block or even Russia solely.. which necessitates other response... (from US and European countries)..
The hoover article is much more militarily focused.. and actually counters your earlier assertion that the west should just send in troops and get it over with.. hoover, known to be a conservative leaning think tank is clear that the west likely doesn't have the ability to drive the russians out of ukraine without creating some serious problems for itself (similar to the problems the russians are now facing.. like running out of weapons systems... when those weapons systems would be needed to deal with other potential near peer threats like... wait for it... China....).. and that supporting the ukranians are the cheaper option to obtain the same goal brookings speaks to.. weakening russia, as a strategic goal..
the hoover article ends with:
"The most likely outcome is a humiliating armistice. Paradoxically, that may redound (contribute greatly) to the long-term benefit of the United States."
If you cant derive what the strategic interests are from those two articles, you clearly either dont want to, or lack the ability.. they are written at a very simplified and basic level..
that doesnt mean you have to agree with them.. I disagree with quite a bit of strategy I see coming out of the pentagon these days, and havent seen anything that resembles reasonable strategy on most items addressed by the white house most days..
but the rationale, recommended methodology (generalized) for execution, and the reasoning behind over arching strategic initiatives related to ukraine are indeed present.. if you bother to read whats been put in front of you..