Then you know what you do?
You send tons of military aid to those nations and you establish a real military partnership. Not treaties of protection, but actual military assets. You make Russia know that it will hurt if they screw with these countries, not give those countries the idea that they can just depend on us to show up and rescue them because they though they didn’t really need a military of their own.
That’s called playing chess. you move pieces so your opponent doesn’t move theirs.
Didn't we try to put in defensive missiles? Now you see why Russia objected. We could do it now as a bargaining chip.