When should secession be supported and when shouldn't it?

[Bunwahaha [still dunno why, but well, so be it]]

Under what conditions should regions of a country be allowed to secede and constitute a new country?

When the Federal or central power allows them to and not a second before.

(or whenever the region in question can defend themselves from the Federal or central power)

Agreed, but if an other country, or an alliance of several ones, wanna support the partition of an other one, why not? Kosovars seem to be happy that NATO permitted their independence. If everyone assumes what it does, and especially to break the sovereignty of an other country in the name of principles or self-interest or others, to me it's OK. The only thing I would ask is speeches to be accorded with acts, and when it is impossible I would like we change speeches. Everyone might have heard about this place named...Tibet...