Burma is an intoxicating country in many ways but among its attractions is this — that in a world of grey areas and moral compromise it is a straightforward case of black and white.

The military Government of Senior General Than Shwe is so squalidly mean and corrupt, and the opposition, symbolised by Aung San Suu Kyi, so uncomplicatedly just and self-sacrificing, that it is as close as one can get in an imperfect universe to a struggle between good and evil.

It is a flattering cause to champion, and over the years many foreigners, as well as Burmese, have looked for ways to do their bit. Few have unwittingly done as much harm as John William Yettaw, the American who secretly swam across Inya Lake, Rangoon, earlier this month to visit Ms Suu Kyi. Ironically, he has given the awful generals exactly what they wanted, at exactly the time they wanted it.

The junta’s detention of Ms Suu Kyi is cruel and absurd but it has always, by its own twisted standards at least, had a token legal basis. The anti-subversion laws under which she has been held are themselves a travesty, but they could at least be contested, however unsuccessfully, by her lawyers. Later this month, with the expiration of six years of house arrest, without trial or even charge, even that figleaf of legal respectability was to have been yanked away from the generals.

Now, thanks to the hapless Mr Yettaw, they no longer need to trouble themselves with legal niceties. His overnight stay in her home — providing lodging to a foreigner is a crime for any Burmese, let alone the country’s most prominent political prisoner — has given them a ready-made reason for locking Ms Suu Kyi up for at least another five years.

Burmese language blogs have expressed scepticism that a lone individual could dodge the police patrolling all sides of Ms Suu Kyi’s house, and speculated that the whole incident was engineered by the Government itself. But the junta has never found difficulty in finding far-fetched excuses to imprison those who disagree with it. On balance it is probably more likely that Mr Yettaw penetrated the security cordon as a result of police incompetence, rather than as part of an elaborately staged charade.

International pressure and foreign activists have a vital role to play in human rights tragedies such as Burma. But, as Mr Yettaw’s example shows, such interventions have to be made with delicacy and judgment if they are not to end up doing more harm than good.

Burma is a romantic as a well as a just cause and over the years it has drawn its share of fantasists, eccentrics, self-publicists and straightforward lunatics, as well as many effective and committed campaigners.

“Naive acts cause more harm than good,” wrote Aung Zaw, the exiled Burmese journalist, on the Irrawaddy website yesterday. “Next time a foreign activist undertakes a publicity stunt, let’s hope they check the depth of the water before they go swimming.”

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