There is little new that can be said here. The attacks are in Europe, and used bombs, so the gun control angle is a non-starter. They took place just outside the airport security checkpoints, as many have predicted would be the inevitable result of trying to set up checkpoints around secure areas. A defensive strategy does not have the resources to present a strong defense everywhere, so determined attackers will find some way to do damage.
One worrying note:
I have to assume this was driven by some specific intelligence. I hope that the people they are sending home are not any of the security personnel.