If the laws of the US are not obeyed, and taxes owed to the US are not paid, then that is an insurrection.
The president has the authority to suppress insurrection. The state does not have the legal authority to start an insurrection, so such an insurrection would be illegal.
Does the Prime Minister of Canada have the authority to put down an "insurrection" if Quebec were to declare its independence,as it almost did a few years back? How about Britain's PM? Scotland is holding an independence vote next year.