The decision to deploy and what types of weapons the national guard troops carry is up the Govoner of each State. This is why you see some troops with only side arms and others with the M-16's.

This brings up the issue that the only reason why they were called up is not to enhance security but to make the public think that flying is safer. In reality, very little has changed since 9/11. If armed robbers can rob $6,500,000 within a secure area at Heathrow, then we still have a long ways to go.