original_query: What are state defense forces and how do they operate?
query: What are state defense forces and how do they operate?
answer: State defense forces (SDFs) are military units operating under state governments, authorized by state and federal law.  They are distinct from the National Guard; they cannot be federalized.  SDFs generally handle emergency management and homeland security missions, often organized as army units but sometimes including air and naval components. Their activities and size vary significantly by state.