I'll disagree with this, too. The NG is an arm (reserves) of the standing (kings) army.
The Reserves and regular duty operate under USC title 10 as does the NG when called into Federal Service. They are subject to the Posse Comitatus Act, as amended, and other Federal statutes which severely limit their ability to act in a law enforcement role.
An interesting note: While the UK has the Royal Navy and the Royal Air Force, there is NO Royal Army. It is the British Army and belongs to Parliament and not the Monarch.
WWG1WGA
Garde la Foi, mes amis! Nous nous sommes les sauveurs de la République! Maintenant et Toujours!
(Keep the Faith, my friends! We are the saviors of the Republic! Now and Forever!)
LonePalm, le Républicain du verre cassé (The Broken Glass Republican)