Secession is illegal. We should send out the army to crush the traitorous rebels!
Secession is illegal. Use blockades and sanctions but refrain from the use of military force.
Secession is legal only if the international community recognizes the new state. Otherwise it is illegitimate.
Secession is legal. States should be allowed to join and leave the union as they see fit.
Secession is legal. I'm moving to that state! Down with the federal government!