Standard gun-licker party line, completely unsupported by history or law.  

The Japanese never considered invading the mainland U.S. because they understood that victory or defeat would depend entirely on naval warfare: their army, already bogged down in China and Southeast Asia, was completely inadequate to a trans-Pacific invasion.  They could barely land a few men on two Aleutian islands, as a feint from the Battle of Midway (which they lost anyway--and along with it, the war).  

 Hitler "disarmed" (i.e., arrested and often killed) Communists, Socialists and other political antagonists long before he turned his attention toward active persecution of the Jews. in 1938.

Our society is one of constitutions and laws, not men.  Written laws--not just those in individuals' heads.  We have administrative agencies and courts whose duty is to interpret and apply those laws.  No right of states or individuals to revolt against the U.S. is recognized.  Insurrection is simply crime.