TACAMO aircraft were the answer to a tactical problem. Communicating with SSBNs (missile submarines) is a difficult business, especially if you can't wait for a prearranged time for them to surface or float a radio buoy. In order to penetrate seawater, radio needs to be in the ELF or VLF range. Sending ELF or VLF messages at long ranges requires enormous antennae; the U.S. Navy maintains several facilities to send these messages which cover several acres each. As a consequence, they're also extremely fragile. In the event of war, especially nuclear war, there is good reason to believe that these facilities would be unavailable. Other landbased links would be vulnerable as well.

The U.S. Navy solved this problem by having a fleet of aircraft that, when alerted, would take off and begin orbiting previously defined positions over the United States. They would form an east-west chain designed to relay messages from the CONUS and Hawaii (and Looking Glass and its ilk) to the Atlantic fleet, especially the submarines.

TACAMO stands for, and I kid you not, TAke Charge And Move Out.