Cameron´s argument that the EU makes UK safer is demolished by Brussels attacks

A spot on comment on a sad day by the Telegraph´s Europe Editor Peter Foster:

Downing Street had hoped to make security a key plank of the campaign to remain in the EU, but on days like today, the very phrase “European security” sounds like a bad joke.
Mr Cameron wants to argue that we need to remain part of European agencies like Europol and Eurojust precisely to prevent terrorist atrocities in Britain, but in the rough and tumble of the campaign that counter-intuitive argument will be hard to make.
Inevitably, attacks such as this – striking at the very capital of the European project – risks deepening the urge among some British voters to retreat behind our borders, throwing up the “Brexit” sign as we go.
Mr Cameron and other leaders will argue that would be a short-sighted mistake – unravelling the same Europe now under terrorist assault – but every new attack renders the argument that the EU makes us safer a little harder to make.