If there is a lesson from the NI police data breach it is not to forget the cruelty of the Troubles | Martin Kettle

The leak could undermine security in Northern Ireland - restoring power sharing is a political necessity at this moment

Half of the people who live in these islands have no adult memory at all of the Northern Ireland troubles. Too many of those who can remember them have allowed the bombings, shootings, riots and violence to slip from their minds in the 25 years that have passed since a peace treaty was signed in 1998. But last week's data leak by the Police Service of Northern Ireland (PSNI) ought to be a wake-up call for the forgetful, and a lightbulb moment for the unaware.

Nine days ago, in response to a freedom of information request whose provenance remains unclear, someone in the PSNI mistakenly put the names, initials, ranks, place of work and departments of all of its 10,000 officers and staff online for about three hours before they were removed. Especially in a profession where police and their families were, and sometimes still are, regular targets, it was a spectacular security breach, even in these more peaceful times.

Martin Kettle is a Guardian columnist