For sure this is destabilizing to the security of the region.
One war at a time though.
Hard choices? There are so many. One is that Russia had to deploy a large number of air defense systems to the Finnish border, and as a result didn't have enough for Ukrainian strike drones. This has resulted in far more penetration of Ukrainian drones into Russian oil refineries and ports than would have otherwise happened, and forced Russia to allocate both capital and manpower to manufacturer larger numbers of air defense systems. Similar tradeoffs happened in other areas. For example Russia built multiple new battalions intended to counter potential NATO operations over the border, but doing this overwhelmed military training sites, forcing its sites to be time-shared and its Ukraine soldiers to receive less training, and its the cost of the Ukraine war to be significantly higher.
Asking this question is like asking if there would be hard choices for the US if Mexico entered a security alliance with Russia or China. Of course there are.