The Westinghouse company, which had sparked the explosion, had been making radio equipment for certain years, mainly for the army and navy, which had been among the earliest users of wireless and radio. Radio became an arcane military activity, on which the public was forbidden to trespass. Civilians could read about it in wartime fiction, which depicted radio as a tool of espionage and of heroic rescues on land and sea. Meanwhile an electronic industry was burgeoning via army and navy contracts, which made Westinghouse, General Electric, and Western Electric into young electronic giants. The army and navy wanted quantities of transmitters and receivers—for ships, airplanes, automobiles. They wanted mobile "trench transmitters", "pack transmitters," and compact receivers. The purpose was to organize a United States- controlled international message service that, by using the air, could undercut British-controlled cables and make the United States supreme in international communication.