And in response to some of the commenters in this thread: of course an independence movement is going to be violent, especially when the state is trying to oppress it. The independence movements in the US, NI, and India were violent too, not because they were wrong but mostly because of mixed public opinion and an oppressive state.
Perhaps if we legally recognised the right to secession and offered citizens a democratic route to secession then violence wouldn't be necessary. Secession movements are going to happen regardless of their legal status.