101^st Signal Radio Intelligence Company

SIGSEC IN HAWAII- 1941-1942

Following the Japanese attack on Hawaii on 7 December 1941, the need to secure military communications became a paramount concern. Unfortunately, the Hawaiian Department, of the US Army, possessed little if any resources with which to accomplish this mission. Aside from Station 5, a strategic collection facility under control of the War Department, there were no other signals intelligence assets available to assign to the COMSEC mission. As a result, negotiations were opened with the Federal Communications Commission (FCC) which did have monitoring sites in the islands.

With funding, equipment and transportation provided by the Army and Navy, the FCC boosted their manpower by 88 personnel and opened monitoring sites in Honolulu, the Punch Bowl, and on Hawaii, Maui, Molokai, Lanai and Kuaui. The stations began a search for subversive communications and other security missions. The Navy curtailed support of this operation when it became evident that classified information would need to be shared with FCC sites.

In July 1942 the Department received reinforcements when the 101^st Signal Radio Intelligence Company arrived. Initially, it had been thought that the company could be integrated with the FCC operation however that proposal was soon discarded. In time, the FCC role in COMSEC was gradually reduced. The company set up Monitoring Station 21 at Pacific Heights and commenced operations.

The 101^st had conventional tasking against Japanese military communications but frequently engaged in COMSEC operations. Mobile DF vehicles were fitted out and employed and the company also functioned as a frequency "cop" looking for unscheduled use of the frequency spectrum which was saturated with Army, Navy, Coast Guard and Air Corps communications. Concern over enemy jamming was raised when the Japanese attempted to jam radars on western Oahu. Mobile DF teams traced the source of the jamming to a point 10 miles east of Kanaohe Bay, at sea. Navy planes depth bombed the area and the jamming ceased.

The natural tendency of US military personnel to "chatter" in an unsecure manner is evident in the following examples from the 101^st files:a soldier in an Army Tank Destroyer Battalion was found to be transmitting personal messages to friends in the South Pacific using a radio which he had modified (without permission).

A flight of Navy aircraft en route to Hawaii from the West Coast engaged in a continual "gab fest" over their radios during the transit. This chatter revealed their destination, positions, various flight data and the location of a convoy spotted along the way. When a coded transmission was sent warning them of their violation of security, the pilots proceeded to discuss the coded message content "in the clear".

During US operations in the Gilbert and Marshall Islands, the company provided COMSEC support and provided reports to the Commanding General and his Staff.The company was redeployed forward to Guam in 1944 and their COMSEC mission devolved on other units by then operational in Hawaii.