General Nipat Thonglek, Permanent Secretary for Defence, sent out the order after naval-enlisted men were arrested with weapons and credentials claiming they were security guards.
The order said that arrests of military personnel with weapons had unearthed evidence of their involvement in the political rallies under the guise of being security guards.
“Military officials under the Defence Ministry must be politically neutral and should not dress up in military uniform to participate in rallies, or flout military discipline and regulations" the order said.