It’s the Federal governments job to protect a state against invasion.
Article IV, Section 4 states:
“The United States shall guarantee to every state in this union a republican form of government, and shall protect each of them against invasion; and on application of the legislature, or of the executive (when the legislature cannot be convened) against domestic violence.” (Emphasis added)
The Guarantee Clause
The text and original meaning of Article IV, Section 4 of the United States Constitution clearly support the conclusion that all branches of the federal government, including the judiciary, are obligated to perform their respective constitutional functions so as to protect each of the states from any kind of lawless invasion that may occur.
The federal government is currently in violation of its Guarantee Clause obligation to protect the states from invasion.
The USC states the feds are responsible but it does not limit the States to do so as well.