. . Operation CTG 7.3 No. 1-53 8. 900, SECURITY &. 910,Silence. No requirement for radio silence is imposed on radio circuits except as may be specifically ardered by CiG 7.3 or higher authority, It is expected that radio silence on almost all cir- cuits will be ordered from several minutes prior to a shot until about one minute after the shot, b. 975,3.__Monitoring of Traf ic. (1) The Army Security Agency (4S..) will provide a commmnication security unit, under the operational control of CJTF SEVEN, for monitoring radio circuits in the Forward Area. (2) All low, medium, and high frequency radio circuits are sub- joct to instant interception from fixed land stations or possibly fron ships, aircraft, or submarines. Under favorable conditions, VHF and UHF transnissions afecalso susceptible to monitoring by unfriendly forces. c. Transmission (1) Principles. The basic principles of transmission security are outlined in ACP 122(B). In view of the heavy requirements anticipated on all circuits, circuit discipline must be vigorously enforced. In addition, the following princivles of security shall apply in the forward area: (a) . No radio circuit (including VHF and UHF) or telephone circuit having a radio link is approved for transmission of classified information in the clear. (>) A221 TOP SECTET and RESTRICTED D:.Ti messages will be enciphered off-line prior to transmission over SIGTCT circuits. (c) Code names will not be assigned to individuals, The use of personal names on voice radio circuits is authorized, (a) Radioteletype, CW, and visual message facilities will be used in lieu of voice radio whenever practicable, (e) Fersonnel operating voice circuits shall be thoroughly familiar with ACP 125, Where time permits, and especially on HF circuits, voice transmissions should be written out and approved by originators prior to transmission in order to avoid the inadvertent disclosure of classified matter. a P50 DNA