Create a regulatory framework allowing the ATF or DoD to Regulate Militias

The second amendment states: "A well regulated militia being necessary to the security of a free state, the right of the people to keep and bear arms shall not be infringed."
Let's balance our approach to the second amendment, and create militias for the purpose of allowing people to keep and bear arms, especially military-style arms. The constitution does stipulate a "well regulated militia," however. There does not currently appear to be any framework for regulating militias. It would seem we are almost 222 years overdue. I would think that DoD might be a natural choice as a regulator, or the National Guard, or maybe ATF.