CLLR Mark Warters (Letters, November 21) proposes that the Government should improve our national security by withdrawing from the EU Schengen Area agreement on open internal borders.

This will not be necessary, as the UK is not a member of the Schengen Area, having opted out in the first place, as did Ireland.

Even so, it is still a problem for us, because its many signatories are reluctant on principle to reinstate internal border checks, and talk instead of strengthening the EU’s external borders.

This is impossible, because the boundaries are often indefensible. They include Greek islands such as Lesvos (an island I know and love) which is a stone’s throw from Turkey and has been overwhelmed.

David Cameron’s policy on Syrian refugees, which Cllr Warters attacks, is an astute and sensible way of offering checked and manageable aid while also fending off pressure from Germany and Sweden, which opened their gates in unthinking generosity and now find, unsurprisingly, they cannot cope.

We should be well aware, however, that we face dangers which stricter borders cannot remove. Most of our potential terrorists are here already, and often were born here, as with the London bombings, and now again in Paris and Belgium.

They are radicalised and motivated by expert use of the internet and social media. There are no border checks which can deal with that.

Peter Hollindale, Grange Garth, York