Unilateral secession is illegal in the United States, but condemning so harshly the referendum efforts of Texas seems morally questionable. I don't see why shouldn't every state have the right to self-determination and sovereignty, if it so wishes. California, Texas or Hawaii should have, in my opinion, the chance to declare independence, as long as an absolute majority, as established by a transparent referendum, is in favour of it. I remember Spain being internationally condemned for not allowing the Catalans to hold an independence referendum, a criticism with which I agreed, although I'm against Catalan nationalism.