I'm still waiting for someone to show me the word or phrase in the U.S. Constitution which would prevent a state from seceeding even today.
It cannot be done.
Those who wish to subjugate the sovereign states fall back on the mantra "there was a war fought about it and it was decided", not knowing they are idiots for proposing that a 'war to end all wars' was said about WWI, yet we still had WWII, and will have more and more and more wars.
WARS DO NOT END ANYTHING, they just settled a certain outcome at the time.