Nah. In that example the UN = federal government. We do conduct missions with the UN. Again, if you were in the forces today, and the US attempted withdrawal from the UN and a UN officer ordered you to fire on US troops, what would you do?
And the Declaration of Independence:
"When in the Course of human events, it becomes necessary for one people to dissolve the political bands which have connected them with another, and to assume among the powers of the earth, the separate and equal station to which the Laws of Nature and of Nature's God entitle them, a decent respect to the opinions of mankind requires that they should declare the causes which impel them to the separation."
Maybe there's something about the right of self-determination you don't understand.
Or maybe you wish the 13 British colonies would re-join the Kingdom.
I don't know which.
But if you believe 13 British colonies had the right to secede, then you must believe that 13 sovereign Southern States, which granted a few, delegated powers to a federal union (and 3 of them clearly stated when they joined that they retained the right to reclaim the powers given the federal government when they joined), and that federal government was based on the power of self-determination, then those 11 Southern states CLEARLY had the power to secede.
Admit it. Lincoln destroyed the very thing the founding fathers fought for.
Or maybe you think ALL tyrant rulers have the power to use military force to force governments on people who want independence.....