Send the Ukrainians weapons and other supplies.
We should not fight Russia on behalf of the Ukrainians.
Talking about admitting them to NATO appears to be a huge mistake. I don't we should have expanded NATO eastward at all. Frankly, I'm not sure what the purpose of NATO is at all now. I am leaning towards thinking the USA should leave NATO. The Europeans can fight their own horrific wars.
There's nothing wrong with treaties. And the US/European trade system inherent to Western life and philosophy is the sole reason for the existence of NATO. As much as I don't like the US as the policeman of the world, the US has every right to engage in international treaties and defense pacts. Every obligation to do so.
What I earnestly want, is the US to stand on the following principles:
1. Defense of the lives of US citizens
2. Defense of the rights of US citizens
3. Defense of the natural rights of all human beings as espoused in the Declaration of Independence
4. Defense of property and trade of US citizens around the world (not to be confused with intrusionary/intimidation based squatting and interference)
There's a hierarchy here, and for the US to act, say, on #3 or #4, then there needs to be an articulable and imminent threat to #1 and #2 to risk American lives in war on foreign soil. And it's important that #3 be above #4 for any action to be moral.
In regards to this quagmire? That's a tough knot to unravel.
I'm confident that the Ukrainian revolution in 2014-2015 that put pro-Western parties in power was certainly CIA backed. I see no difference between that, and the Donbas and other separatist action in the west of Ukraine whose name I cannot remember, which are both fomented by Moscow in interest of Russia.
Putin is looking at this in two facets.
1. Territorial defense. In a classic ground invasion, he wants a front that is as small as possible to make it easier to defend. The Warsaw Pact era pushed such a defensive line all the way to Germany. If Ukraine joins NATO that line stretches from the Baltics to the Black Sea and is indefensible.
2. Economic interest. Russia has a near-monopoly on oil sales to Europe. If Ukraine begins operating its own oil interests, it can use oil transport infrastructure that the Soviet Union built and paid for, to compete with Russia for European market share.
I think that the pre-20th century perspective on territorial control is effectively dead. Territory is a liability, when all is said and done. It's nothing but infrastructure demands, "peasants" to appease, and territory to monitor. Resources certainly matter, but those can be accessed even on foreign territory through trade and development agreements and private property rights. Putin's economic perspective is in some ways in conflict with Western notions, but then again, a lot of US foreign interventions have been couched in counter-terrorism but have involved US investment in resource development in the offending country.
Ultimately I see Russia as having breached the Budapest Memorandum of 1994, when it comes to addressing Ukraine today. However, the Budapest Memorandum effectively has no teeth, and does not obligate the US to participate in defense of Ukraine under the current conditions. France and China supposedly granted Ukraine security assurances related to the document, but not the US, or Germany/Poland/NATO/anyone else. I don't know what those security assurances entail.
I don't see this invasion as a threat to the US, as sad and distasteful as it is. It's not a genocide/extermination event; we don't have Jews in gas chambers or racial concentration camps or anything like that. It's a territorial annexation with the intent of gaining economic control/leverage. The market it impacts is Europe, not the US.
Europe has a population of about 750 million people. Russia accounts for perhaps 150 million, and Ukraine about 40 million. There's 400-500 million people living on the European continent that are members of NATO without counting the US. They have several of the strongest economies in the world and a strong manufacturing base.
Europe can handle this if they want to. The US should sit back and be the MAD deterrent, holding the NATO charter prominently. If Russia introduces nukes into a Europe-led ground war, then it's time for the US to get involved as the NATO treaty dictates. If Europe is the primary party that wants Ukraine into the EU (and possibly NATO) then Europe can handle it. No offense has been committed thus far that requires the US to get involved in a Europe/Russia conflict.
