In London a man accused of hacking into the computer system of the Pentagon and Nasa is waiting to see if the House of Lords will hear his appeal against extradition to the US to face a trial in which one prosecutor has already indicated he should "fry". Blowing up an airliner is clearly regarded as less serious than causing major embarrassment to the defence establishment.

Luis Posada, a veteran anti-Castro militant and CIA operative under George Bush Sr, was told that he was free to go due to administrative errors in the case against him for entering the US illegally. Posada is wanted in Venezuela and Cuba for allegedly plotting to blow up a Cuban airliner in which 73 people died in 1976.

The US authorities have already indicated that they will not extradite him to either country, and all the other states to which they have sought to deport Posada have refused him entry. No wonder his lawyer remarked, without apparent irony, that "he is very gratified that the system has worked".

Gary McKinnon, the young Scotsman accused of hacking into the Pentagon and a variety of other US military and space-research sites from a room in a flat belonging to his ex-girlfriend's aunt in Bounds Green, north London, is awaiting the decision on his appeal against extradition. The home secretary, John Reid, has already given permission for McKinnon to be sent to Virginia for trial, and it is unclear what kind of penalty awaits him. Since the magic phrase "9/11" has been mentioned in connection with the timing of his hacking activities, it seems unlikely that McKinnon will be told that there has been a technical error in his prosecution and he is free to go.

The Posada case has caused concern inside the United States and outside. Last month a Boston Globe editorial noted that "the administration is treating this case with delicacy, perhaps because of the CIA connection. Who knows what dirty dealings he [Posada] might reveal? ... Yet justice for the deaths of 73 people should outweigh any concerns about ancient CIA revelations." The editorial also suggested that Posada should face trial on the murder charges either in Venezuela or the US. Under a 1971 international convention, a nation that refuses to extradite a suspect in an airliner attack is obliged to try the person in its own courts.

The Non-Aligned Movement, which represents some 118 countries - whose support one would have thought the US would value in the "war on terror" - has also expressed its concern. Yesterday it issued a statement that called on America to fulfil its obligations under the United Nations charter that proscribes the harbouring of terrorists.

McKinnon is accused of causing $700,000 worth of damage to computer systems, but his greatest offence seems to be that of causing extreme embarrassment to the US defence establishment. His alleged offence, which he has always said was prompted by a desire to know if information about the existence of UFOs was being suppressed, was committed in London. As such, he should be tried in a British court.

Perhaps if he had concentrated his undoubted technical abilities on damaging Cuba or Castro, he would now be enjoying the freedom of the city of Miami and a trip north to Disney World, where he could, presumably, discuss the state of the US justice system with Mickey Mouse.

duncan.campbell@theguardian.com