As the situation worsens, we may have to consider doing the same as in WW2, when we had possible enemies within. Germans living here were either interned if deemed high risk, or tightly supervised if considered a lower risk All must be considered the enemy, unless there is very strong evidence to the contrary. A more rigorous screening process may prove necessary in the near future.
As for comparing ROP jihadists to the Irish troubles, there are two elements that make the situation we face today far more worrying. Considering the comparatively short time that the ROP have moved in large numbers to Western Europe, the problems that most of us could foresee have started growing at an alarming rate. Secondly, it is a lot more difficult to fight an enemy within that isn't scared to die. I don't believe that the Irish on either side wanted to die for the cause. However, ROP terrorists have no fear of death.