You keep comparing Afghanistan to Ukraine. The Afghans have been fighting foreign invaders, the government in Kabul and when they aren’t available, neighboring clans since the beginning of time. An Afghan mujahid could survive on a greasy piece of nan bread and a pocketful of rice for days on end. They could climb the ice-bound mountains in their bare feet and learned how to shoot when kids in Ukraine were still learning their ABC’s.
I have met Ukrainians, they’re nice people but I have to tell you they ain’t Afghans, plus the sort of people who oppose Russia are the middle class urbanites who want to join the rich man’s club of the EU, not the sort of fighters you need when Ivan is breathing down your neck.
One other point the Afghans were fighting the Red Army for four years before the US supplied them weapons, they were taking pot shots at helicopter gunships with 70-year-old Lee Enfield rifles.
When the Ukrainians show they can fight like that we might consider getting involved. Mean time stay the hell out of the Bear’s back yard.
Stepan Bandera and his band of guerrillas fought the Red Army for over 10 years in the 40's and 50's before being defeated after the Soviets massacred hundreds of thousands of civilian supporters. We'll see if today's Ukrainians are worthy successors. Note that the Cossacks are the ancestors of modern-day Ukrainians, and they've been fighting the Russians for hundreds of years. The difference is that unlike Poland, they were unsuccessful in staying out of Russia's clutches. Note also that Carter began funding the mujahideen months *before* the Soviets invaded, in order to destabilize the communist government that had replaced the Afghan King.
Another problem is that for a massive country/empire like Russia, a lot of countries are in its backyard. Afghanistan was in Russia's backyard. So was Iran, which Stalin wanted to annex.