Borders are sacred, in that they are not to be violated with belligerence. Nuclear weapons created a dilemma of maintaining peace which is solved, partially, with this agreement between countries. This means there must be compromise when it comes to whether or not Donbas or Crimea is administered by Ukraine or Russia, or themselves.

There is a trade, and if a person is ignorant of history they might not understand the trade and think it is ok for Russia to take their town because they consider themselves Russian. That is not acceptable to a world that must remember the consequences of discounting peace.

The moment Putin used force to take that land, he jeopardized the hard earned lessons of the necessity of peace in the nuclear weapons age. And those that support or apologize for it are willfully ignoring the consequences of discounting peace when nuclear weapons exist.

If I value peace, and think those who support or at least apologize for this war discount it, why do I support a continuance of the war? Because it would be fatal for the free world to forget or ignore what happens when a fire isn't put out soon after it starts. I use fire as a metaphor because I think it's apt to the situation. A fire doesn't stop burning because you ask it to. Neither will Russia.