Trident nuclear missiles were designed in the 1980s to kill 10 million Russians.

These days, loaded onto submarines, they sail endlessly around under the world's seas, threatening nobody in particular.

With their fearsome capacity for mass destruction and death, nuclear weapons have always been immoral. Now, in the age of the suicide bomber, they have become supremely pointless.

But nuclear warheads can also be dangerous to those whose job it is to look after them. The Sunday Herald has often reported on the accidents, leaks and blunders that have plagued nuclear submarines, and their bases at Faslane and Coulport on the Clyde.

Today we reveal the dramatic fears of a young submariner so shocked by what he saw and heard at Faslane and on a Trident submarine that he felt he had to risk imprisonment to warn the public. Able seaman William McNeilly, now on the run, has written a genuinely frightening report.

The picture he paints is like a kind of bad disaster movie, where almost everything that could go wrong does. There are fires, leaks, floods, failed tests, false alarms, broken equipment and security breaches. The toilets don't work, a missile compartment is used as an exercise gym, and there are doubts about whether missiles could actually be successfully launched.

McNeilly may not have fully understood all he witnessed, and may sometimes be overly flowery with his language. But his report must be heeded. His suggestion that security is so poor that infiltrators could easily access the world's most lethal weapons is very disturbing.

Too many of the problems he highlights ring true, and have been suspected or hinted at before. We know from previous reports that the Royal Navy has long been struggling to recruit enough skilled nuclear engineers.

That's why the Navy's decision to launch an investigation into his report is welcome. But it must be independent and transparent - and fully answer all the allegations made.

McNeilly is a whistleblower and must not be treated harshly - even if he has broke the rules. He seems to have had good motives, and it would be wrong to punish him for acting in the public interest.

Crucially, his revelations should reinforce Scotland's determination to get rid of Trident - and hasten the day when its sinister dark shapes stop sneaking in and out of the Clyde.