You're lucky I've raised 3 boys or I'd tell you what I tell them: Look it up, I'm too busy drinking beer to do your homework for you. But, since you're not my kid and since you're new here, I'll give you a kickstart.
This whole business in the Kerch Strait seems like a set-up to me. Russia has nothing to fear from the Ukrainian Navy, so why the provocation if not to ratchet up the perils of another clash or incident giving Russia pretext to invade its former satellite state?
Putin's got the Crimea sewed up, he's got a bridge spanning the Strait. Ukrainian vessels passing underneath pose little threat to him. If he just wanted the Crimea, he's got it. Seems to me he's getting ready to roll. And if he does, does anybody think NATO is willing to go to war with him over it?
Ocoka - any speculation on the size of the Russian move on Ukraine?
Smaller hybrid force attack on Mariupol/slow expansion of the eastern occupation?
Or a full scale overtly Russian annexation of eastern ukraine/fight for all of Ukraine?
Somewhere in between? Neither?
(introduction post taken care of years ago, long time lurker but rare poster)
Putin has no reason to roll into Ukraine proper. The purpose of instigating a sessession in Donbass was to distract from and seal the Crimea takeover, while eliminating any prospect of potential NATO membership by creating a territorial conflict. His greatest opportunity to take the rest of the country was right there, in 2014 when it was drown in chaos and there was little to no physical threat in the way and also nearby. The UA may still not be any major threat to the Russian military and I doubt NATO would intervene directly and waste it's NRF and whatever air assetts it can scramble in Europe, but it's barely the same situation as back then when nobody expected it and wasn't ready. He is also risking to bleed out his military in a large scale conventional war and subsequent resistance if the Ukrainians refuse to give up their country. It may not be the same as fighting an insurgency in the North Caucasus as people there can be extremely vicious but if they were forced to, well Ukraine is a much bigger fish to deal with.