The US defence department has called on the groups of armed citizens who have sprung up to patrol outside military recruitment centres to stand down.
The groups have appeared in the wake of the killing of five service personnel last week in Chattanooga, Tennessee and have taken up the role of unofficial armed guards.
The Pentagon made a delicately worded requested for the groups to disburse, warning of the potential security risks of having armed civilians on patrol near the centres.
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A Pentagon statement said: "While we greatly appreciate the outpouring of support for our recruiters from the American public, we ask that individuals not stand guard at recruiting offices as it could adversely impact our mission, and potentially create unintended security risks."
The statement said that Ash Carter, the US secretary of defence, was reviewing safety recommendations for the centres.
US recruitment centres are typically in public areas such as shopping centres and the military personnel who man them are usually barred from carrying weapons.
Groups of armed civilians began appearing outside the recruitment centres after a gunman killed four marines and a sailor in Chattanooga, Tennessee.
Muhammad Youssef Abdulazeez, a US citizen of Middle Easter descent, attacked two facilities shooting four people dead and leaving a fifth fatally injured.
He was shot and killed after a standoff with police.
Ed Reinhold, an FBI special agent said on Thursday that it was too early to determine whether Abdulazeez had been "radicalised" prior to the attacks.
(Additional reporting by agencies)
