We cannot rely forever on the incompetence of our enemies but we should enjoy it while it lasts. The bucket bomb on a London tube this morning was undoubtedly intended to kill and maim as many people as possible. That it failed does not diminish the malevolence of its makers. It was no more discriminating than the lorries and cars driven into crowds around Europe this past year have been; in a horrible way it was even more nihilistic than the abominable Manchester bombing, which targeted music lovers, whom some perversions of Islam would see as sinners. But it failed. Shocking and frightening though the experience of the tube passengers must have been, it could have been very much worse.

By now, the responses to these attempted atrocities is well practised. The politicians express shock and disapproval, the police get on with their work, the commenters of all shades of opinion prepare the pieces explaining why this has proved them right all along and – in this year’s development – President Trump says something crass and unhelpful. As is always the case with his tweets, there is no way of knowing whether what he claimed is actually true: did Scotland Yard have the perpetrator under surveillance? If it had been true, he would have once more been guilty of tweeting out classified intelligence just as he did after the Manchester bombings. But it seems to be just another example of his capacity for quick-witted confabulation. It’s notable, though, that Mr Trump’s tweets drew a public rebuke from the prime minister and from the Metropolitan police, who both called his remarks “unhelpful”. It’s another example of the growing lack of trust in his judgment. That is not a result of any terrorist campaign, effective or otherwise.

Today’s assault looks reminiscent of one 12 years ago, shortly after the horribly successful tube bombings of 7/7, when another attempt was made to bomb London using homemade explosives packed into buckets. The detonators went off, but the explosives did not catch. This may be what happened today. If so, it is a tribute to the effectiveness of long, slow and unglamorous efforts to cut off would-be terrorists from the sources of the knowledge and skills they need to make an effective device. The 12 years that have elapsed since the last attack failed in this way are a reminder, though, of the really uncomfortable aspect of today’s: if, as seems likely, one or more of the perpetrators are young, British-born men, they will have grown up through 12 years of argument, pressure and persuasion against terrorism, delivered through mainstream Muslim opinion, all of the mass media, and even the Prevent programme, without this making any impression on their willingness to kill innocent people. We can’t know how effective this pressure has been in turning other young men away from violence, but it is obviously not sufficient in itself. That’s no reason to give up, but it calls for a realism about the outcome of our efforts.

In fact, the lack of excitement in this country has been one of the most encouraging reactions. There have been no calls for fresh powers for the security services. It is a tragedy that these attacks should come to seem predictable and almost routine, but if they must become a regular feature of British life, as they have been for more than a decade, it’s best that we not get too excited. The terrorists want to rouse terror and the kind of anger which quenches reason. The phlegmatic reaction of the country at large is all we can actually contribute to the struggle, but it’s important and we should continue to keep our heads over what is by any reasonable standard a pinprick attack.