Mr Bevan, who was arrested in June last year, was alleged by the USAF to have used the Net to access and alter sensitive research and development files at its Griffiths Air Force base near New York, and the Lockheed Space and Missile Company in California. After his arrest by British police in June last year, he was said to be part of a "phat" - a worldwide Internet hacking group.
But yesterday Andrew Mitchell, for the Crown Prosecution Service, told Woolwich Crown Court that it was "no longer in the public interest" for an expensive and lengthy trial to take place. He said: "The court's hands are tied as to sentence and the role of this defendant was secondary to that of another who was dealt with by a fine ." Three not guilty verdicts were recorded.
Afterwards Mr Bevan, dressed in a black suit andsunglasses, refused to comment and was escorted away by two tabloid reporters.
He was initially arrested during a police investigation into the activities of Richard Price, a hacker who at the age of 16 was known as the "Datastream Cowboy" for having hacked into computers at Nasa and USAF bases. Earlier this year Mr Price was fined pounds 1,200 for 12 offences.
Detective Sergeant Simon James, from Scotland Yard's computer crime unit, said afterwards that the incident may have had "serious implications" and cost Lockheed and the USAF $500,000 (pounds 312,000) to sort out their computer systems.
Simon Evenden, Mr Bevan's solicitor, said: "He is delighted. He has been waiting for this for 17 months and can now put it all behind him."