Quote Originally Posted by Montmorency View Post
So the UK had reason to contest German self-determination (though honor toward Poland wasn't ultimately a significant factor).

Again you conflate a number of different questions.

What is a matter of deserts and what is a matter of consequences? Whether or not you believe British foreign policy is a direct cause of terrorist attacks, it's a petulant display to treat a country like a sports team fanatic, endlessly whingeing about it but calling it the pinnacle of oppression when non-fanatics offer an opinion too. This is a question you need to give proper consideration regardless of whether the actions of terrorists are right or wrong.

The self-determination of domestic radicals isn't that of countries, these being different kinds of entities; you shouldn't apply the term to individuals at all, in fact. Domestic radicals are additionaly your countrymen, and the actions they undertake are usually straightforwardly criminal under British law. Don't try to apply concepts to inappropriate contexts.
And there is the salient point. They were born here, but their parents weren't. And radicalism does not decrease with each successive generation, but it's the younger generation, born here and raised here, who cause problems. If we can't remove these from the pool as they're our countrymen, why should we further add to that pool? After all, future prospective incomers aren't our countrymen, but outsiders from another country.