The US military has advised its staff to treat armed civilians standing guard outside its recruiting centers as a security threat.
The groups started appearing outside military offices in various states after a gunman killed five service members at a Tennessee Navy facility.
Some have argued that the deaths could have been prevented if the recruiters had been armed.
Typically military recruiters do not carry weapons.
Mohammad Youssuf Abdulazeez, 24, opened fire on a recruitment centre on 16 July in Chattanooga. He then drove about six miles (10km) to a Navy and Marine reserve centre, where he shot and killed four marines and one sailor.
Some military personnel were armed at the second location.
