From Security Studies Group:

The militia is the vehicle for invoking the power to dissolve the government by force, which is a power the citizenry retains inalienably per the Declaration of Independence. Likewise, the militia is one of the final vehicles for protecting an upholding a state the citizens continue to approve of against insurrection or invasion. The citizen is the officer of the state that holds the final say on both of these matters, and therefore the militia properly belongs to them.