Militarily or economically. They also have to realize that the west will give them loans they can never pay back, not gifts. If they can't do the "independence" thing without being independent, what the heck do they want?
The colonies waited until they were given assurances from France that they would back them before they declared independence. We had already established at least one country that was willing to provide military support before we made the move to separate from Great Britain.
The Ukraine has no military ally. They are not in a position to take on Russia alone. If Putin wants all of the Ukraine, he has no obstacle in front of him.
After the Ukraine comes Lativa, Lithuania, Estonia and Poland. Did I leave anyone out?