The Selective Intelligence Communications Robot, also known as the SICR, was a machine that was developed by the United Federation of Planets Starfleet. It was designed with the intention of travelling across space without being detected by enemy sensors. In addition, to prevent it from being discovered, it was capable of being programmed to self destruct if it did not find its target or if it was tampered with during its voyage.
In 2267, the SICR was dispatched by the Federation Defense Council with the intention of finding the USS Enterprise in order to stop a possible Federation-Romulan War. (TOS novel: Web of the Romulans)