Why would Denmark need to partner with any of those places? The EU is neither poor nor weak (sure, we'd think twice about getting into a war with Russia, but so would anyone, US included). We're quite capable of securing ourselves.
I'm kind of curious if, emboldened, Putin will make a grab for some, all, or bits and pieces of the Baltic states. That would really cause the shit to hit the fan, and Europe to have to decide if they can and want to defend their borders.
Nah. He hasn't even sorted out Transnistria, which would be much less problematic than the Baltic states from a legitimacy point of view.
I personally don't see Putin as this evil dictator... He plays a very old game, yes, but this also means he's very predictable. He didn't get into Crimea because "he wanted Crimea", he did it because the alternative (his only major Southern port in NATO hands) would have been a disaster from a strategic perspective. As I keep repeating, would the US let Panama slip in Russian or Iranian hands? Of course not.
Denmark could choose to be neutral. It worked for the swiss, a small country with high mountains and not a lot going for it. But just imagine that poland had said to Stalin and Hitler, before WW2: "Hey, fight your wars without us, we'll just stay neutral!"
The danger of Russia as a neighbour is not its size, wealth or military power - the US+Europe have more of that - but the willingness to play rough.
Neutrality for Denmark and its neighbours means no benefits from alliances and all the negative aspects of regional competition...
Danish Defense has 24,000 active personnel. Of course it depends on the level of conflict, but I would argue that Denmark couldn't defend itself against much more than some internal unrest.