Despite the nonsensical claim that Russia likes "frozen conflicts", when it comes down to it, Russia would rather get the war over fast.
Russia has a pattern of sudden attacks against targets:
Russia’s invasion playbook generally proceeds as follows: positioning conventional forces on the borders of the targeted country to amplify political pressure and organize for invasion; infiltrating special operations (Spetsnaz) units to prepare and spearhead the incursion; seizing a strategic airport through airborne units; and airlanding additional assault troops to secure the battlespace and decapitate the national government in conjunction with the already inserted special operations units.
The authors include Czechoslovakia 1968, Afghanistan 1979, Crimea 2014, and Ukraine 2022 as examples.
Of course, the examples also included sending those conventional forces poised at the border across the border.
But I wouldn't count Crimea (Ukraine) given that the target wasn't a national capital and because of the unique circumstances that contributed to Russia's success.
The authors advise countries to allocate units to defend key airports; for America and its allies to train those units; for America and its allies to provide intelligence warning of the playbook unfolding; and for resolve of the local leaders to stand and fight rather than flee and create a power vacuum that Russia can claim is a reason to name a puppet government that Russia has identified.
The authors notes that Moldova and Georgia could be targets. Although it should be noted that Russia did not try to do that in Georgia in 2008. Russian ground forces advanced on the Georgian capital, but could not reach it.
I think Estonia, Latvia, and Lithuania could be targets, too.
And really, it's good for Taiwan to take this lesson to heart:
Taiwan’s Taoyuan International Airport became the scene of a simulated Chinese invasion on Wednesday for the first time ever as the island’s military conducted an anti-takeover drill to fend off any possible attack from Beijing.
Lots of people say an amphibious invasion across the beaches is too hard for China to successfully carry out. I think airheads are the main threat. I think China will go right for the jugular. Including by sea.
UPDATE: Related relevant information for Taiwan.
NOTE: The image was made from DALL-E.
NOTE: TDR Winter War of 2022 continues here.