Sun Tzu, in the ancient classic The Art of War said I think that the first rule of war is to avoid war, but the second one, if war is unavoidable, is to win.
These are just some thoughts -- any experts on the subjects are welcome to correct them. I'm thinking that as Afghanistan was allowed for discussion, defence situation regarding Ukraine is probably allowable (without getting into party politics). If the mods disagree then they are of course welcome to close the thread before it takes off.
The West has poured trillions into Iraq, Syria, Afghanistan, places with arguable results but without a major standoff against the other two superpowers. During that time, Russia and possibly China, have developed hypersonic missiles with strike capacities that are hard to defeat while the West is still in the research stage. In other words, the West is not in a great position to engage in a fight with Russia, or Russia and China combined. Now we are in a position with Ukraine, which means much more to Russia (or Mr Putin) than Syria or the other places. Ukraine is not part of NATO, so the West has no obligation (But Poland of course is part of NATO). Sanctions might simply raise the stakes.
If Russia takes Ukraine, the West, among other things, will freeze assets of many Russian oligarchs in the West. Bad for Russia, but might not harm Putin's position and so have limited effect on Russian warmongering.