Afghanistan-lite? The Ukraine situation seems much worse than Afghanistan.

Re regret, I guess it depends on who you mean by 'Russia". Looking at their faces I think most Russian top officials apart from Putin were rather horrified from the start.

It can't afford to. It will be instantly recognized as an admission of weakness in the snake lair.

For as long as Putin's regime stands, klepto elites around him will be sure that, at least within Russian borders, they are still kings, and they can live the rest of their lives surrounded by long legged mistresses, and drowning in luxury.

If Putin is seen as weak, any small time gang will think that moneys, and power of Russia's top oligarchs are for grabs. It will be then, when a preemptive coup attempt can happen.

Do you mean regret a proxy war with US?

That wasn’t exactly the primary issue with Afghanistan.